AMD 64 X2 Dual Core Processor 4400+ 2.21 GHz
3GB RAM
NVIDIA GeForce 8800 GTS
Ice, I'm no expert on these things, so don't take my word for it, BUT...
When I first realised we had to upgrade for the coming cryengine, I went and got a
Nvidia Geforce n9800GT (made by MSI).
It did not work properly. It crashed frequently, sometimes with enduring effect.
(I think the onboard GC memory got written over, making the card unusable until what was put there faded some 4 or 5 months after removal. Maybe that's crazy, but I don't know what else explains why it worked after reinstallation, but only after that time period.)
From what I read at the time, the 9800 was a rebadged 8800, with a few extra features. I don't understand enough about it to know exactly. What I do know is that, with only 2GB memory, and that card, it couldn't cope. Processor is merely P4 3GHz.
I took the plunge and bought yet another card - an nvidia GTS 250 1024MB GDDR3 (by Gainward). Works fine. No problems at all. I get very occasional screen freezes for 4 or 5 seconds, but only if I am running other applications,Once in a while when there's lots of action (so certainly its occasionally frustrating). But it works well.
I still only have 2GB RAM. I could actually put in some more. I think 32bit Windows XP Pro is limited to 3.5GB RAM. Not sure.
Anyway, sounds like your processor is better than mine - I wouldn't know - and you have more RAM. I reckon your card may be the culprit. It is the older series of cards. My old one was supposed to be really an 8800 in disguise and it was no good - actually something radical went wrong with it when cryengine is loaded. No one at Nvidia, who were working with MA on the transition, had any idea - at least, the support cases I put in never had any useful response.
It may well be that the superior processor and RAM may not be enough to counter some qualitative deficiency in the card.
Finally, I note that, while mine would crash, sometimes permanently, yours only goes slow, so all I have said could be entirely wrong. All I know is I've had no problem at all since going to the new series of cards. There are better ones than mine, but mine seems to go ok.
Hope all is well.
I finally saw lance, but I haven't seen him for months. I thought I must be gaining on him in Hit Levels, but no, not a chance. He's has been skilling away on the 5K Trox quest and is Lvl 60. I'm languishing at 54.
He's Marvellous while I'm only Amazing.

Anyway, I still can't really play due to exams and other commitments. But It would be nice to catch folks occasionally.
Cheers,
ram