I currently have my non HDTV 60" Philips/Mag hooked to my HTPC via S-Video right now till my "Ebacherville Home Theater" is finished, I have a ATI 7500, it looks ok for DVD and Divx (we have watchmany movies), not quite as good as a standalone box via S-video however... But Destop or applications look like crap... very fuzzy.
I have done this with many diffrent video cards and scan converters , you have to spend quite a bit of money on a scan converter to get good results....and quite a bit means close to the price of a budget projector... Kind of makes it a mute point..
I would look around an find some one here thats getting rid of a older PJ or check out the CRT fourm.. They can usualy direct you twards a cheap source for a older CRT.. If you were close to me I could get you a used Zenith CRT for $200.