Anima:
I think Raška and Zeta kinkgdoms are both dated in 7th century. I am not sure but I think Zeta kingdom (today Dolnja Dalmacija) was the first and later spread to innerland to Kosovo and Metohija teritory and in 10th century added Macedonia and reached border maximum in 12-13th century before Otomans become too strong, defeated Constantinopol and finally won the battle at Kosovo Polje in 13th century.
Maybe there was some Croat kingdom in Poland like you wrote, but I would say Slavonian kingdom is the first official state of southern Slavs who later formed to modern Croats.
As far as differencies. Language is the same, origin is the same. Your culture and mentality is the same. What`s the difference between Croats and Serbs? You all are very temperament and able in a second turn from the best friend into the worst foe and stab somebody with a knife if if he says are makes something what you consider to be abusing you...
Religion difference? It`s just the matter of being in different sheep-fold in the past. You willingly joined Hungarian kingdom and accepted catholicism while serbs remained out of Hungarion territory and kept the original religion brought by Konstantin and Metod priests from Solun (Thessalonike in Greece) who were wiped out from Great Moravia (Slovakia) after making agreements with Franks and adopting catholicism which was the first step to fall of national independence and become slaves of Hungarians for almost 1000 years. I consider religion for a political tool, not for a national habbit. After all, who now trusts the God and goes to church? It`s only you and serbs and some people in Slovakian villages are still religious fanatics, but the rest doesn`t care.
Bosnians are nation? Without J.B.Tito "Bosanci" would never exist... I still don`t undersatnd how someone religious preference can promote to national character. That`s incredible. Especially if Tito was communist fighting against all churches. That guy really massed up YU...
Montenegrians are Serbs, the only difference is they have never been conquered by Turks or any other foreign power becouse of tough terrain. Small armies very easily destroyed and bigger ones starved and had to return home. That`s the only difference to Serbian Serbs from my view. However it`s ridiculous when Montenegrians want to loose independence and surrender without fight even if never in their history were conquered by foreign force...
Dobro, dosti bio istorije...
How can I "adjust virtual ram"?
It seems buyng another 1GB RAM is a must... Wow, another 120$ thrown away... :-(
BTW I am playing CIV4 on huge map with 15 civs. I am sure on Tiny map with 4 civs my HW would be enough, but playing it this way is no fun.
That would be great if making a mod with SLovaks! As far as Slovak leaders. Svatopluk is definitly the greatest Great Moravian leader but he was from Morava (modern Czech Republic) and defeated Pribina, earl from Nitra (city in Slovakia) kingdom to unify slavic tribes. Maybe "Pribina" would be better name than Svätopluk who is isnt so purely connected with Slovak teritory like Pribina.
Uff, modern leaders?
I think you definitelly should consider the name of father of Slovak national identity forming during romantism in mid 19th century - Ludovit Stur. He is for slovaks the same what Jelacic for Croats. He led the slovak uprising against Hungarians in 1848. Died on the impacts of injury (officially he had shot himself) during hunting in 1857 (i think so or a year like that). Hungarian influence on his death suspected.
20th century significant politicians?
Even if not being very politicaly active in this century, there are still few names:
1) Milan Rastislav Stefanik - Leading member of foreign Czechoslovak legion fighting together with Frenchs against Axis in WW1. He together with Czech Tomas Garyk Masaryk (first Czechoslovak president 1918-1938) formed first Czechoslovak republic in 1918 and suddenly died in airplane crash (most likely Czechs were behind this) near Bratislava in 1919. His airplane was hit by "invitation salve" while landing...
2) Andrej Hlinka - Catholic priest fighting for Slovak authonomy under Czechoslovakia during the first Republic (1918-1939). You can see him on Slovak 1000 SKK bank notes. Died in 1937 normal way. No uncertain circumstances suspected.
3) Jozef Tiso - president of first independent Slovak state (kao Nezavisna Drzava Hrvatska) during WW2. Opinions on him differ. For some people he was the one fighting for Slovak interests who managed to get the best from the very difficult political climate of those times who managed to keep Slovakia independent of direct German control (in spite of Czechs and Moravians for example) and refused to take part on Nazi ethnic cleansing of Jews as much as possible, but for the others he was nothing just a Nazi traitor.
Hanged on gallows in 1945.
4) Alexander Dubcek - Political leader of "Prague spring" in 1968 which ended by army intervention of Soviet army and their Warsava pact allies.
Died under uncertain circumstances in car accident in 1992 on the highway from Bratislava to Prague. Political interests on his vanishing from Slovak political scene before "constructing" (People were and still are against it) independent Slovakia in 1993 suspected. Certainly somebody thought having too strong political person beloved by many people was too big setback for their plans with this country.
5) Vladimir Meciar - Political puppet taken from somewhere especially known like a person who became a "father" of Slovak independence. After finishing his role, he was pulled down from the stage in 1998. He`s still alive and leading the 2nd strongest political party.
I don`t know how many political leaders you need. But I think Pribina (eventualy Svatopluk), Stur and Stefanik should be there. They are the most significant ones.
BTW, who is Jan Golian? Hehe, I didn`t know somebody made Gasparovic being a Croat... I know stupid people from the west (eg. Bush) can never remember the difference between Slovakia and Slovenia but i hear about mistaking Slovak with Croat for the first time... :-o
When I was in USA, nobody knew about Slovakia. Even if sombody who served his military service in Bosnia managed to react positively, he always just did wrong with Slovenia. I think if an American asks Slovaks if know eg. Tennessee, Conecticut, Vermont surely at least one of 10 people would know where aproximately this state could be...
Unique unit? We never had own army and don`t have specific Slovak named military type. I think the best known "Slovak" military unit are Otoman`s "Janiciari" `couse they consisted of many our boys like of other Slavic nations as well.
Or "Husari" special cavalry, but this is more typical Hunagrian, than Slovak military unit... We are pacifists. Mi tucemo samo picke ciganske, siptara ili majmuna koji dolaze iz prasume...

I think what`s typical for Slovakia and especially for it`s mediaval age is being the Europe no. leader in mining and foresting. The first mining university has been built in Slovakia, Slovaks were the first who developed forestry system of dividing forest to 70 parts regulraly cutted and planted used now everywhere.
I think best Slovak special unit should be "Slovak worker" building mines, cutting and planting forests twice faster. Definitelly not building roads or railroads, this action should take 2-3 times longer. Just compare the speed of building Croat and Slovak highways! If working at our rate Split is highway connected with Zagreb MAYBE in the year 3000!
BTW, if speaking about roads and railroads. Hungary has the highest railroad density in the world and practicaly 99% of Slovak railroad network has been built under Hungarian monarchy. I suggest Hungarian workers build railroads two times faster.