Ok, your system need serious help and you don't have much cash. The first option (especially if you're a gamer) is to get a nice vid card and then save up for a new mobo, CPU, and RAM. I would favor this route instead of sinking more cash into an obsolete system. You can then migrate the vid card to the new system.
Second option would be to sell your old stuff off to help pay for a new mobo, CPU, RAM combo. An AMD combo might be the cheapest, but an Abit BH7 and P-4 2.4B would not be a total budget buster. Then you'd have to get by with your old vid card until you can afford another.
The third option is to upgrade your vid card to maybe a Radeon 8500SE ot 9000 Pro, then get a Tualatin Celeron 1.1A and overclock it to 1.5 gig. If your mobo don't support Tualatin CPUs, you'll need to get a Powerleap adapter. If you have no hope of saving up any cash in the near future, this might be the way to go. You'll have the old CPU and vid card to try and sell at least.