Globetrotter - np, will get on it.
sabo - there are 2 ways rushing cultural buildings can help to prevent a flip:
1) To take tiles from an AI civ in the city's 21 tiles. For example, if an AI civ has 3 of 'your' 21 tiles under it's control those count against you. If you gain that back form cultural buildings the chance of a flip will drop.
2) To get more 'local' culture in the city than the 'other' civ. For example: Persia owns a city and gets 80 culture in it. You capture the city and so there is a x2 modifier to flip chance (called 'local culture' (checkbox) in the flipcalc). If you get 80 or more culture in that city the x2 modifier is lost and flip chance is reduced, since the AI doesn't have more culture in the city than you anymore.
Note that for many AI cities the local culture is huge, often several hundred or more (especially if the city is lold and the AI built early temples). In this case you would need a temple and library for maybe 100 turns before the flip chance is reduced by the x2 modifier.
Personally I don't bother rushing cultural improvements, unless it is for reason (1) above. That is not very often since I normally try to carry the attack on to take all their cities. If I can't I will opt to starve the city to size 1 (I do this in 95% of cases).
