you can put your vista repair disk in.
if you do not have one you can make one, download this:
http://neosmart.net/blog/2008/windows-vista-recovery-disc-download/
You need a torrent program to download, so lets start of with download Bitlord from bitlord.com and choose stable version, now download and install, now click http://neosmart.net/blog/2008/windows-vista-recovery-disc-download/ and download which ever one your windows is, i'm gussing it's 32bit, anyhow, download it via bitlord and then when it's done follow this
http://neosmart.net/blog/2008/windows-vista-recovery-disc-download/
goodluck man
So is it possible to install this if your windows wont boot up?