Seems I was very stupid... 20gb is NOT enough for a vista partition... always used to be plenty for other os's.. they would maybe take 2gb up.
Vista takes 15gb!!!!
When I last checked, before SP1 it was 12gb
What, then can be deleted? (I do not like the idea of starting again, or playing with resizing tools)
Im now oof to find some dvd burning software.. as the windows one is useless. Try to burn a dvd, it first makes a copy in a temp folder, and then it makes a disk image, which is also a copy. So to burn a 5gb dvd, you need 15gb free in total! So I have no hope on this partition....