I understand how you feel man, game was unplayable for me from the time AHII came out until just the other day. I cussed and pulled out plenty of hair. Finally I had to face facts that no matter how many guys are lucky enough to get by with old systems and video cards, I aint one of em. A new MOBO, new power supply, new video card and a new OS later, I can play with good frame rates and no problems. The new processor thats on the way should help even more. Main reason it took me so long to get the game playable was I didnt have the money for all these things and had to stretch out the purchases; and still, I've done without other stuff to get my upgrades. But it was worth it to me. Maybe you can find a way to get by with what you have. My guess is though, you are hitting the end of the road where software and hardware are going to be compatible and your games still be playable. I found alot of good advice in different posts on this BB, and found more on other BBs until I had a good picture of what I needed to do. I suggest you do the same and start drawing a picture of what you are going to have to replace. You can get frustrated and quit, like I swore I would do a hundred times. But at the end you are still going to have the same computer and same hardware you have now, which is only going to get more dated with time and be less compatible with new software.
I wish there had been a cheap and easy fix for my problems that would have kept me flying, even if I had to give up alot in the graphics and frame rates for a few months until I could afford the upgrades better. There wasnt. Best of luck to you in your efforts.