Good luck getting WCIII to run well on your machine. I have a 750mhz with 256Megs of Ram and a 16Meg video card. Not great, but far beyond what Blizzard recommends. I have to turn down all the textures, shadows etc. to get it to run. When there is a lot of action on the screen, it is still VERY jumpy--almost to the point of not being able to play the game. You need at least a 32Meg video card. Don't get a Voodoo card either, everyone has a lot of problems getting WCIII to work with them.
Good luck.