Xfx 4850 1GB

hi-

i recently purchased a xfx 4850 1GB from newegg.com

i was expecting to be able to play crysis at 1280X1024 at high settings, is this reasonable?

i get ~25fps when just walking around but it goes down to 10-15 when i'm owning (explosions, jumping, vehicles crashing, shooting, etc). i was expecting better than this

my system:
xp pro 64bit
4GB hyperx DDR2 1066 (2X2) (running at 800, more stable when overclocking)
7750 black edition 2.7GHz (sometimes overclock to 2.9)
320 GB 16MB, 7200
4850 1GB, sometimes overclock clock/memory by ~50mhz each using CCC
jetway HA07 (integrated radeon HD 3300)

i dont think my processor is bottlenecking because it doesnt go 100% when playing (~75-80)


also- on a different subject, should i overclock the PCI-e link?

thanks alot