1) create msdos boot disk and copy files format.com and fdisk.exe or download a bootdisk of the web
2) Back up ALL your files.
3) restart computer with boot disk in it and floppy set to first. It will boot into a dos prompt. Type format c: (where c: is your windows hard drive) If you want to config partition, use fdisk.exe
4) change the boot procedure in bios to Cdrom first, then your hard drive.
5) Put in your windows cd in, and follow instructions.
6) Get latest drivers, updates, virus protection, firewall of a friends connection because if you connect to the net on a fresh version of windows, youll be infected with a virus or spyware very quickly.
7) Put you files and programs back on.
Core 2 Duo E6400, DFI Infinity 975X/G, 2x 512mb DDR2 667mhz, Albatron 7900gt, WD 200gb SATA, Samsung DVD-RW, Silverstone ST-50EF 500w PSU.