What to do?
AMD X2 3800+ 2 Ghz
Would it be advisable to upgrade these components if I wish to play UT3, and if so, which would require the upgrade? Also, how does the motherboard and more specific RAM properties come into play? I'm still new to these things...
Try the demo. It's the best way to see if the game is playable with your current specs.
The best boost will come from upgrading your video card to an Geforce 8800, 9600 or Radeon 3800. Forget SLI and Crossfire, there's no real advantage on the Unreal Engine 3.
If you're on XP, 2gb of RAM is fine. If you're on Vista, consider 3 or 4gb.