Check the specs on the new version of ah2. Luckily, they just cant afford to make a game aimed at playability on your system.
Sadly your computer is so old, that a new vid card wont help you much.
I have just suffered a motherboard meltdown on my lab computer, so I have been searching for a replacement.
For an amd xp 1800+ system including motherboard, chip, ram, and even the box for less about 250 dollars (if you like nicer ram). You can get a 9600 ati for around 80 bucks, and ah2 will seem like a whole new world.
http://www.newegg.comand
http://www.accessmicro.com both have good deals. If you dont know how to build your own, I suggest the later.
edit:
I just checked it out, and at accessmicro you can configure a full system with a crappy, but better than your vid card, and amd 2200+ (using your harddrive, cables, cdrom, floppy, keyboard, mouse, and modem) for 263 dollars.
http://www.accessmicro.com/estore/config/index.cfm?config_id=219&OptionSet=3