That'll be 533MHz, dickz.
ZOMG I cant believe it... your pc is so similar to mine!!
I have an MX 420, not 440, and I have 450MHz not 533, but we have the same amount of RAM.
Firstly make sure ur playing in OpenGL. Secondly, you must must must download the latest renderer (get it here:
http://cwdohnal.home.mindspring.com/utglr/dxglr18.zip)
Then, once that's all set up, delete say, type preferences, goto rendering, make sure the following are set to FALSE:
Volumetric Lighting
ShinySurfaces
DetailTextures
HighDetailActors
Then set detailmax to 0, it should already be on 0. The game looks lush when it's set to 2, but your FPS will suffer.
Set the LOD to about 1.5-2. This will make everything blurry, so set NoFiltering to TRUE.
Goto the display bit of preferences menu (close rendering bit), make sure curved surfaces is set to false, and set all detail thingies to low, ultra low wont work.
CLose the prefs menu, exit dx, then reload dx.
Welcome to my world.
EDIT: Btw clix, dunno bout him, but my pc reaches around 58 degrees celsius after being on for around 20 mins. That's processor temp, measure from BIOS, so probably innacurate!