Oblivion help, Please!

[markharrington777]

I am an avid roleplayer. A slight newbie when it comes to learning stuff. The only stupid question is the one not asked. My computer (Compaq Presario, AMD Sempron 3200+, 512MB RAM, with an ATI Radeon Xpress 200) is ok for now. I can run and play NWN2 (with minor glitches) and my favorite, Oblivion. Now, Oblivion plays well with no issues when I am in a shrine, ruin, underground, but when I reach the surface, or the "real world", I come into stop frame glitches. It is especially bad in rain. How can I remedy this? Please help. Thank you.