intel pentium D dual core processor both 3.40 GHz
2Gb DDR2
Radeon HD4550

i installed the patch and the preview v2.0 AMD drivers

not sure what graphic settings i should have for catalyst and also in game

If anyone could please give me a hand just so i can at least figure out if im completely screwed or if im just doing this wrong
that would be great

I remember reading a thread saying that the game worked better with 'Hyper Threading' turned off in the bios. You could try that, but maybe let people know exactly what kind of errors you're getting and somebody should be able to help you .
Also, make sure you have +jobs_numThreads 0 in your Launch Options (via Steam) or at the end of the "Target" Line (if you've made a desktop shortcut).

Good luck.

im getting the really bad checkerboard texture corruption problem as well as texture pop in. i dont believe my cores are hyperthreaded but i suppose i shall check
the launch parameter i already tried and if anything it made my texture problem worse

i cant believe i spent 60 bucks on the amount of hassle this is.

hey dude. I feel for ya!
I will be writing up a topic with exactly how i got mine running super stable and exactly what settings i've used. I've practically got no issues now(except minor sound sync issues) where textures load almost immediately in an area but don't keep reloading on sudden movement. Also my in game FPS fluctuates from 14 and 35 but texture loading/streaming is so good that you barely notice. In the main menu the FRAPS counter was saying fps at 60+ so who knows you may even get a better overall performance than me.

Will call the post "My personal fix for dual core and 4xxx" and it will contain full details - i just hope it works for you like it did for me...