windows updates won't install (fail)

[Coreystaf]

Dell 530s
windows XP sp2
Internet explorer 7

My computer is very new, less than a month old and when I go to Windows Update, the newest update is SP3. It downloaded fine, but when I try to install it, 2 or 3 seconds and it says that the installation has "failed"
My PC came with XP sp2 and I had already installed sp3, but I downloaded a photo editing software and as best as anyone could tell, it corrupted something to the point where windows would not even begin to startup, couldn't even start in safe mode.  It ended up that we used the XP disc that came with the computer and reloaded windows.  Everything seemed ok except the failed updates.

[Coreystaf]

UPDATE:
about 10:30 last night while using my computer, the power in the house flashed off, no storm or anything, just seemed like a normal flash and everything in the house reset.  when my computer (always plugged into a standard surge protector strip) started rebooting, it went the DELL bios version screen and stopped with a cursor in the top left corner- nothing else.  I went in thru the boot menu and was able to boot manually.  not sure if all problems are related but driving me nuts!!