Windows xp (media center) boot problems!! :(?

guys, need your help please.. Windows won't boot (not even "Safe mode, tried it). My Dell computer starts fine, I click F8 whatever shortcuts I take just shows the windows logo and then blue screen. Even debug mode, everything just gives me the blue scren. I want to reinstall windows xp format my hardrive (it was a virus a few days ago who started this) but Dell computers apparently don't have a Windows CD with them. Friend told me to create a bootable floppy but computer dosn't have a floppy drive. Is there anyway to fix and keep my original windows without installing a pirated copy? Don't want to go there. Don't care much about formatting if I had too luckily had a backup of almost everything.. TY