XP won't load, linux barely loads

Maybe this is two separate problems? Windows XP will go through the POST, but then hangs at "Windows is starting up" and never does load. I can start in safe mode sometimes, but it usually just goes to a black screen. I ran Linux Mint from a live CD and was finally able to boot, but it took 5 to 10 minutes and showed several pages of error codes. I don't know what the codes were because they go way too fast to read. I just now realized I could have hit the pause button; maybe next time. All power supply voltages are in spec and I've loaded default "safe" values in the BIOS. What can cause both a no start-up from the hard drive (XP) and real slow start-up from the CD (Linux)?

Mobo is a Gigabyte GA-M78SM-S2H with an AMD 4850e CPU. Nvidia 8200 video. 4 gigs of RAM.

Any help is greatly appreciated!