if you installed windows xp from a cd without a previous windows alredy installed then it could just be a matter of creating a boot disk ( choose from any of the following, pop a floppy in the drive and create it : click here ) then restarting your computer, if your computer is setup to boot from the floppy drive first then the hard drive then it should start churning away, if it doesnt you will need to reboot and at the bios menu look for the option to change boot order (possible something like f11), boot from the floppy and to format your hard disk (if you just want a quick format it takes a few seconds, but a full format can take many minutes and depending on your hard drive size, possibly hours)
to do a quick format type at the command prompt:
format c: /q
and to do a ful format just miss the /q off then end to give you:
where c: is the drive letter of your hard drive you want to format.
once your computer is clean from all those bugs, remains of killed off spyware, virus remains and such, you are ready to install windows again :)
pop your windowx xp disk in the computer and hit the reset button (gently :) ) and make sure your computer boots from the cdrom drive, all being wel you should have the windows setup running and be back up in no time, however. if you are one of te unlucky souls that picked up an upgrade only disk you will already need to have version of windows already installed (windows xp setup can't be started from dos - to the best of my knowledge).if all goes well we shall see you on the other side :) , but if all doesn't go well "borrow" a friends computer for a while and come back to the forum for some more help with any little quirks or niggles you may have encountered :)