Re: graphics card help
as Suxor said, they will work.
PCI-E 2.0 x16 and PCI-E 1.0/1.1 x16 are backwards compatible and vice versa. As long as they are PCI-E x16 it should work.
You will only see a difference in them benchmark programs, but when playing games, watching videos, etc, there would be no difference since theres not card out there that can use up all its bandwidth.
Desktop -Cooler Master NV690/AMD Phenom II X4 965 BE/MSI 880G-E45 Motherboard/2 x 2GB DDR3 G.Skill Ripjaws X/Sapphire HD 5870 1GB GDDR5/CORSAIR CMPSU-550VX/Seagate 7200.12 500GB (OS), Samsung F3 1TB (Storage)/Sony DVD Burner/Windows 7 Professional 64-bit