I know this doesn't solve your problem, and frankly, I don't know enough about PCs to give an answer based on such skimpy information, but I do know that it isn't as horrible a deal as you think it is.
AE does NOT make great-looking H.264 files. It can't, because AE can't do multipass encoding, which is what's necessary for really good looking H.264 files. you'd be better off doing the encoding to H.264 in a different application, like Adobe Media Encoder (or whatever they call it).
Ooooohhhh, I can't resist! Say hello to Mr. Natural for me, Mr. Crumb!
Keep On Truckin!
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA