LFS runs very well on high settings with a middle-range PC. While waiting for my new PC (still 2 weeks pay away
), I'm using this:
CPU: 2.4Ghz Pentium 4
RAM: 2x 1GB Hynnix PC3200, 2x 512MB Hynnix PC3200
GPU: 128MB Radeon 9800 PRO - swear by this card. Hasn't seen me wrong in 5+ years of service
Motherboard: Standard Dell crapology
PSU: Again, standard 250w Dell crap
Everything cranked up full, still topping out ~100 FPS, haven't seen it below ~30FPS, unless I use a lot of AIs, or a huge AutoX layout. Obviously putting in ridiculous amounts of AI it goes low...
The parts you're looking at will almost be overkill, especially for LFS. You should be future proof for a while at that. While you won't be playing Crysis 2 on full settings, you should be confortably playing new games in a years time on decent settings