After my buddies power went out, it came back on, but the power supply unit fried on his HP Pavilion a6433w.
I put a new power supply in. Now, the power button does something. Weird video "interference", though, after Windows start screen.
HP Diagnostics fired up, and the cpu, memory, harddrive, and boot path all checked out ok with the HP Diagnostics factory program (and I could see the test fine on the screen)....so the "preboot" video can be seen fine on the monitor. But, after the "Microsoft Corporation" & status bar indicator that goes across the screen disappears, I get a yellow, thick horizontal line across the screen, near the top, with a barbershop-pole like (sideways, though) bar across the middle (red and black), and another thin line across the near-bottom of the screen.
He's got Vista SP2, with updates, and a nice, wide-screen monitor. His graphics driver is (for integrated graphics) ADI 198x Integrated Audio Driver Version A09 (SoundMAX).
I booted with a real old Packard Bell ("VLMF") monitor (15 yrs. old, maybe, but it goes to 1024x768).
Maybe it could be from him having a refresh rate set higher than this old monitor could handle.
Well, I would have checked the refresh rate; but, since I was able to see the HP Diagnostics (hitting F9 at startup), and also see the F12 boot menu, I was thinking the video card was ok, and that it MIGHT be the driver got messed up.
Also, I couldn't see the end of the boot sequence, so I couldn't choose anything like video settings....couldn't even find the desktop.
Maybe I will plug in another monitor, unless anyone has some more advice.
(This dude let his firewall expire, and I was hoping to save his pictures and stuff; but, I'm trying to avoid taking his harddrive out and putting it in another computer, if I can [before I restore his HP to factory settings]).