[quote]Can I reinstall windows without screwing up my Kubuntu installation?[/quote]
You can but you will wipe out the grub bootloader. Just make sure you reinstall Windows back onto the partition you had it on originally. Here is the Ubuntu documentation on reinstalling Grub bootloader after you are finished reinstalling Windows.https://help.ubuntu.com/community/RecoveringUbuntuAfterInstallingWindows.
[quote]At around the same time I downloaded and installed the latest release of KDE ( KDE 4.whatever ) It couldn't be that could it?[/quote]
No, KDE download in Kubuntu does not affect Windows.
[quote]Windows is knackered. I recently booted windows to download & install some printer drivers and I think I may have picked up a virus along the way.[/quote]
If you want to just try and see if you can rid yourself of this virus and keep your original Windows install, then join this forum here http://www.d-a-l.com/help/spyware-adware-viruses-hijackthis-logs/ and follow these instructions here http://www.d-a-l.com/help/spyware-adware-viruses-hijackthis-logs/32403-read-first-important-instructions.html before you post your problem.
[quote]Does linux allow for the installation of another OS as dual boot?[/quote]
Yes. This thread in Ubuntu forums covers it.http://ubuntuforums.org/showthread.php?t=747452