putting your OS in a second partition is only a added means of security. it will help contain certain viruses, and if your OS goes down, you can still get access to your files on the other partition(s). be aware that the install files are put into windows in most cases,even though the program(s) might be on a different partition. so you might not be able to run them with a new OS install. another thing is, you might loose one of your data partions, which can make the whole thing pointless. just something to think on.
Biostar T-force 4U,Opteron firstname.lastname@example.orgGhz.CorsairXMS DDR500-2gigs,EVGA7800GT CO.Seagate160gigSATA II,Koolance ICM 510 watercooling,Coolermaster Stacker830