Bandwith is basically how much you send out (upload) and take in (download) those two games shouldn't be a problem (unless you have like 2 computers playing it 24/7).
As for the games, get WoW, I've played both (currently playing WoW a bit) but FFXI was terrible
... It was so slow, it took me about two weeks of playing to get to level 7.... Wow is faster, simpler and generally more fun.