I agree get a new power supply. But Radeon's are very picky when it comes to drivers. You must remove all ati (or other video card drivers, like your intel extreme drivers) programs from the add/remove programs list then run a FREE DRIVER CLEANER
to remove all the other junk that is left behind.
Then install the Chipset Drivers, from the sounds of it you have a via chipset, So you should install the latest via chipset drivers
Then install all the drivers/software for radeon cards (must have .net frameworks first) from ATI.COM
And its very confusing when someone hijack's a thread with their own question. Why not start your own justinone