Those number are REALLY LOW for your system. Check all the basic stuff, including Direct-X version. Also be sure you didnt instlal your video card drivers over the old ones. If so, delete your drivers, reboot into standard VGA then re-install ( recomend newest beta drivers...they rock).
Also be sure you dont have anything sneeky going on in your system hogging resources.
I run a 1.3 Athlon 256 DDR and a Radeon 8500, and at 1600x1200 32bit 2xFSAA 16x Antistropic whatever, and my frame rates are 30-45 on the ground at a large field (with some smoke) and quickly raise over 50-75 once off the ground or a few hundred yards from a large base.
Theres something needs tweeking