Graphics glitch?
 

After downloading from steam on saturday I have had constant problems, starting with seeing the desktop only when in mission, not sure how I solved but since then pathetically low fps anyway. I have tried most solutions and even on low and windowed I barely reach 30 fps with occasional choppy movement over sea. I have noticed that everything outside the cockpit seems to re render textures constantly which may be the cause of problems as fps drops during this, anyone else notice this or know how to sort it?
On low and medium settings its a worse looking game than the last!
Funny from other posts I reckon this would play better on my Mums low spec pc.
(Btw 2.5Ghz Q9300 on Asus mobo, 4gig 800Mhz ram and dual 8800gt, nothing overclocked just ran Crysis 2 on top spec! - disabling sli hasnt helped)

Additional: After doing camaign first mission and pressing esc as asked, it says I failed the mission when in game said I completed? Have not found related solution so thought I would add to above.
Thanks for any help!

73 views and no posts, doh. Anyway, after the kegetys mods it seems a tiny bit smoother, though I think the fps its showing is below reality as it says like 15 but feels in the 20s.
Thought I would give this game a bit of time so looked for something to play in mean time. Saw Bioshock 2 for £3.49 on steam so thought what the hell, finished downloading this morn and it wont launch at all?? Never had any issues with any other games until this lol, ahhhh! :S
(soon to be getting more ram and a better gfx card from the supported list hopefully - had been pondering upgrade for a little while anyway)