The OP explicitly mentioned that he doesn't have access to a credit card, so how should he get the game from Steam? I'd also recommend neither the Complete Edition nor Steam though. Getting one of the cheap re-releases of Civ4 together with the two expansions (or only BtS since it includes everything from Warlords except the scenarios) from a store is the best option imho. Or asking a friend with a credit card to buy those from an online store.
In any case, the OP already mentioned that he resorted to piracy to solve his "problem", so he shouldn't expect any more help from my side (that he isn't able to deal with mdf files is a case of poetic justice imho).