Either processor should be fine for LFS, even for s3 (probably
).
If your going with an 8 series card, you will want to go with Vista to
take advantage of the new DX10 technology, which I've heard ASR
will be taking advantage of, though not at the initial release.
If your not really stretched for cash, you might also want to run duel graphics cards, which will also require a compatible motherboard.
Someone else with a little more knowledge should be able to help you more,
especially with an apropriate PSU and cooling, but i'd thought i'd give my input anyway.
Good luck.