Ok, i posted before about this performance issue i'm having, i had several responses, and the main one was to upgrade my RAM.
So i did.
The problem is, it still runs laggy, hardly ever over 30fps.
AMD 64 3700+
ATI Sapphire HD 3870 512 MB
Windows XP home edition
Things i've done:
Downgraded/updated my graphics card drivers.
Changed the DX sound support to basic.
Changed settings to low with 800x600 res.
Asked UBI support.
Upgraded my RAM.
Asked lots of people, there doesn't seem to be a reason.