I'm not sure if there's anything else.
My dad took an entire day to get everything set up, and it was working great. Later, after a botched attempt at installing Sims 2, I got a black screen with white text saying that "Windows did not shut down properly" and gave me some options.

I tried safe mode, I tried starting up normally, and none worked. I got black for a bit, a blue screen popped up to quickly for me to read it, and it went back to the black screen with white text. I looked around on the internet, and someone suggested I reinstall Vista. I really should have known it would be too easy.

I tried to start up Oblivion, and I got a message saying "Failed to initialize renderer. NiXAdapterDesc::GetDeviceCaps() failed."

Dungeon Siege 2 gets me "A fatal error has occured and the app must shut down.

Unable to enumerate any DirectDraw devices installed on this system.

[Note: This error can occur if another application has exclusive control of the display. For example, Netmeeting's desktopsharing feature may be enabled or you are trying to run this app thorugh a remote desktop in Windows XP or Terminal Server. It can also occur if your hardware does not support 3D acceleration or if your video driver does not properly support Direct X 8.)"

Age of Mythology started working after I managed to get internet connection, but it plays the pre game videos then I get a black screen with the pointer on it.

These games had NO problem before.

If anyone could tell me what is going on and how I can fix it, it would be greatly appreciated.

Time to reformat and reinstall - find some Vista install guidelines for your comp or motherboard (Google is a friend) that include motherboard chipset drivers RIGHT AFTER Vista install, etc.

Oblivion would be the first game to try - stable and well made.

If it runs, then add the patch(es).

Edit: btw: I think this area is for Linux ! LOL

Have you run all the updates from Windows (Mac-Bootcamp) Update?

Thank you so much CCT! It's working now!

So just to re-confirm
It was drivers that needed to be updated on your Motherboard or Video Card? that solved it.

After a fresh install of Windows in bootcamp the first thing you should do is put the Leopard disk in the drive while booted into Windows and install the bootcamp drivers - these contain Apple's Windows drivers for their hardware. I would also suggest that after you've done that you make sure you have bootcamp 2.1 installed - these are updated drivers from Apple, but for certain devices it requires you to have already installed the initial driver set from the Leopard disk.