If you have installed LILO or GRUB, they won't go away just because you nuked a partition. They're burned into the boot sector of the physical disk.
To remove a non-Windows boot loader and replace it with the standard Windows boot loader, start up Windows, then execute command "fdisk /mbr" at a command prompt. This tells Windows to rewrite the master boot record.
Of course, the safer route would be to nuke the Windows partition and avoid next week's virus attack.
