Crysis Warhead / DoWII performance

Hello folks, first of all I would like to say hello to everyone and also say that Toms Hardware site has been my site of preference in terms of news, references and comparison, I have several doubts about the expected performance of my rig:

GB UD54P
i7 920
Ati4850x2
HDD WD Black 1TB 32mb cache

Crysis Warhead runs between 30-45 fps having everything maxed besides physics and shadows, which I put on Gamer instead of enthusiast, I am wondering if this is normal or if i´m missing anything regarding software or hardware : / My goal is to get at least 45-50fps average, what do I need to do/buy?

than you for your early response bpogdowz, would an 4890 Vapor make the difference? How can I reach 3.2 with my i7? I´m afraid of heat, is there any guide out there, can I take as a reference any guide(even if the GPU and mem is different?)

lol, I have now OC my i7-920 to 3.2ghz and I see a mayor improvement in games but where I can really notice it is in Crysis Warhead, to bad that I got that horrible glitch were you start to fire chickens, do you happen to know how to solve that issue, from what I have read patch 1.1 would resolve the problem but there is no No-C|) (R4ack for it : / but I guess that would be another topic.