It would complete the loop of trouble-shooting the components. 300W is plentiful to test an installation, as long as it has a 24-pin main connector, an EPS 12V 4-pin connector and a 6-pin PCI-E connector for the 9800GT as a minimum.
Unless you have another GPU.
I know it's a pain somewhere, but that PSU could be the problem. I would try that even before buying a new SATA DVD burner.
I agree with you on this one, but since he may have access to a second PSU why not try it before spending on a new DVD burner.
I remember helping another member a few month's back with a similar problem; the outcome was a dead IDE DVD burner. Then a week later his PSU died...
I'll give you that, but if he can't find a secondary drive laying around and doesn't want to spend on a new DVD drive, there is another way he can install Vista;
To the OP, if you have a spare copy of XP laying around, try installing XP first. Then plop the Vista DVD in, copy the Vista DVD to a new folder, call it "SETUP", take the DVD out and run "setup.exe". If its a DVD Drive that vista simply dislikes, well you'd be installing it from the HDD so you bypass the optical drive entirely.
Only downside is its a time consuming process. Personally I'd just bite the bullet and get a new SATA drive, cheapest I can find.
Edit - In response to above post, I agree with John, its worth trying a different IDE cable, yes.
No dice with the new IDE cable. Looks like I'm off to the store to get a new DVD burner.
Any other ideas I can try first?
Also, any idea why it takes forever to get between screens during the vista install? It was nice and snappy on my Athalon 64 3000+ but my new rig is over twice as powerful but it takes forever. I know the important thing is to get Vista installed but I mean the slowness is an annoyance.