Wow. I've had my Hack suddenly turned off before and while it booted slower, it was nothing a little Repair Permissions couldn't fix.
It does sound like something's gone wrong with the hardware. Perhaps your video card's on its way out the door? All the fancy effects in OS X will tax your video card and will be far more likely to bring out a defect in it than boring old XP's DirectDraw and some testing (if nothing else then purely because of the way OS X calls the hardware).
However, this could also be a PSU problem (not giving the video card enough juice because it got b0rked by the power loss).

If I were you, I'd test out the PSU and try replacing the video card (with the same model if possible), then reinstalling again.
Good luck.

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Custom Hackintosh...AMD Athlon X2 5000+ (2.6 GHz) on GA-MA78GM-S2H...Linksys WMP300n Wireless...ALC889a sound...ATI HD 3650 PCIe...1 GB DDR2 RAM...320GB Western Digital SATA + 200GB Seagate IDE HDD...Rosewill DVD-RW IDE...Running Kalyway upgraded to 10.5.7...All Fully Functional