A GTS 250 will be fine without any AA. Should keep you above 200 for the most part.
If you dont want to go SLI, you can get a $70 motherboard and a $50 PSU. a 9800gtx+/gts 250 will go around $120 with a good sale. Athlon II 240 costs around $60.
case: anywhere from $50-$100 depending on quality
Mobo: $120-140 for ability to go SLI
CPU: $75-150
Ram: $40-100
GPU: GTX 285 is going for $380, and that'd be necessary for minimum of 120 fps with max aa/af. Too bad you can't go ATI =(
PSU: Might want to be able to go SLI, so around $90
hard drive: $40-100
optional extras: $50-100 more.
Windows 7: $105
$1000 to be safe.
However you could go dual GTS 250's for $260 but I'm not sure how well LFS uses SLI.
If you didn't need max aa/af, a gtx 275 would be fine.
Is it just me, or has the UF1's steering rotation been decreased? It seems like I have to turn my g25 more for it to take a corner. And it doesnt take very tight corners well..
Since you're going to be going ATI, and your PSU will have enough wattage to go Crossfire, I'd recommend a Crossfire capable board. And it's easier and cheaper to find on on the AM3/AM2+ platform.
So I'd recommend a Phenom II 955, any 790fx am2+ botherboard, and a Xigmatek heatsink to match since it's better than the AC7.
There is little to none of that nonsense in S2 racing servers, since if someone does it and they get banned, it's their MONEY on the line. They're not anonymous as well, so it's their reputation if they ever want to join a league or team. Overall, it's much more professional on S1 and S2 servers.