I recommend what icefire. Go into safe mode, but more importantly try out a linux livecd. I recommend
MEPIS. Mepis is very easy and fun to use for intermediates like grimper. Mepis has surpassed what use to be knoppix's domain for the utility livecd for diagnosing problems, testing hardware, and fixing problems with. Mepis is also installable so you can put it on the hard drive do cool stuff like dual boot. Ubuntu as a utility livecd...yeah right. I haven't found the livecd session on ubuntu cds for anything better than sampling ubuntu before you install.
Using a livecd to delete files on a windows install is usually what i end up doing regardless of being in safe mode or not. A livecd is the only way guaranteed that i can delete or plain old manually backup system files without them being in use by windows.
But, yeah grimper, get mepis. Great utility livecd to have around even if you're a windows user. You can get ubuntu if you like, but i have a feeling you'll get tired of ubuntu where as mepis is a much cooler toy.