|ok, for a clean instal you have 2 options:|
1. run your vista installation disk from windows and select install.
2. run the installation disk from boot. go into your bios and set the first boot device as cd rom, and restart.
for keeping existing files, you will have the option when installing from boot if you want to format you hard drive or install on a partition of your hard drive. select the partition, and windows will create a folder called windows.old which you will find in c:/my computer/
Vista nVidia Evolution SP2
Intel(R) Core(TM)2 Duo CPU E6550 @ 2.8GHz
XFX GeForce 9800 GTx
4GB OCZ Platinum 1066
2x Samsung 1TB Spinpoint F1