i had three 9800 gtx+ 512s running and it would lag a little on video and i couldnt run AA. when i baught two 570 superclocked and ran them with my system there was no problems at all, ran smoother than a babies bottom,lol.
this was my old system that i sold( just the main parts):
EVGA P55 200 Motherboard
i7 core 860 2.8ghz-CoolIt Liquid cooled set up
8gigs of ram at 1333
2 EVGA GTX 570 Superclocked in SLI
Kingston 1000watt power supply
Nvidia Edition Mid-tower Case with all 120mm fans
that computer rocked everything from SH5 to BF 3.
now im looking just to run SH5. ive priced some parts and ive rang up a grand total of about 1600 dollars and thats the whole computer with monitor and sound system, mouse/ keyboard, etc. but im still going back and forth with V-cards and going SLI or not. So all of your input is very helpful.