First I would get 256 megs of more ram then maybe think about getting a geforce3 or 4 card to get better icandy or better.
You should really run IL-2 at 32 bit color to. The ground do's not look much better but the clouds do.
Your getting about the proformance you could expect with your rig.
make sure you close all programs running in the back ground you can get away with, to have more memory to run it better.
try turning off any screen saver u have running when playing. Don't for get to turn them back on later.
I based my advice so you can save the most money
added O and update to the latest version will help with frame rate on some *puters