turn on the computer, push f2 right away to get into the bios.
Goto boot sequence and make it so that cd/dvd is first boot device.
Put your windows install cd in the drive, save and exit your bios changes and restart.
When it says "push any key to boot from cd, push any key !"
there you go...
also, its ''gx620" nice solid systems, i've owned several of them.