Basically, my computer has done this before, and somehow I fixed it those times, but the problem seems to be getting exponentially worse each time.

My computer (custom built: 4200 AMD X2, 2 GB ram) can get through its bios POST fine, runs normal, but once it starts loading Windows (XP and Vista), it takes about an hour for windows to actually show its GUI.

For Windows XP (on 2 74GB raptors in RAID 0 in NVraid), it shows the Windows Loading screen forever.
For Vista (on a 320GB SATA), it tries to get to Vista's Recovery tool (all text), and I can watch it draw the lines, and print the letters one by one.

I've tried resetting my BIOS (alot) (it worked the first time), I even just left it unplugged and battery from the cmos out for over 24hrs, still nothing. When this happened before, I have absolutely no idea how I fixed

This started Happening when I used Windows 7 Beta (with sleep mode on, which i heard gave other people problems like me with USB mouse/keyboard issues), but the first time involved it coming out of sleep with Windows 7, then the computer wouldn't load anything at all, so I just cold reset it. Boom, messed up.

The last thing that happened to my computer recently was it was running (in XP), then tried to adjust the resolution, the rundll.exe broke, leaving everything unable to be done, so cold restart. Boom, messed up.

When I wait for it to boot up, the mouse moves around fine, and once things are loaded, they popup fine, but it thinks its running the CPU at max. I think it might have something to do with the SATA controller, because it seems like when its trying to get data from the Harddrive, it takes a long time. I tried it with an IDE harddrive (also giving problems), turned off the IDE controller, reset, turned it on, booted Ubuntu from it, and it loaded Ubuntu like normal

Please help