Umm, you would have to either A) re-install Windows on your D drive, B) do an image copy of your C drive to your D drive (wiping out what's on it) and boot from that, or C) Buy a new hard drive and to A) or B) to that.
Can I assume from the small sizes of your drives that they are older-style IDE drives?
By the way, there is a way to get rid of all the $NTUninstallKB... directories. Two ways, actually. You could just delete them all, and hope that nothing breaks. Or you could read this guide (searches the web for it... ... ...)
http://users.beagle.com.au/alvian/remove_winupd_backup.html .
But you should really treat yourself to some more storage.