the game is so old that those are the system requirements :
Minimum Requirement Recommended Setting
OS Windows XP or later Windows XP or later
Processor Pentium 4 or equivalent Pentium Dual Core or equivalent
Memory 1GB RAM 1GB RAM
Hard Drive At least 7GB of free space At least 7GB of free space
Graphics Video Card with 128MB or higher GeForce FX5000 / ATI Radeon 9600 or higher (any video card with Shader model 2.0 or higher)
Sound DirectX compatible sound card DirectX compatible sound card
Network Broadband internet connection Broadband internet connection
you can see you dont need a really good GPU to run this game, the only reason its so intensive is because it uses alot of sprites
The system that gets 85% physical memory after running 3 instances of this game is pretty good
I have 2 gtx 460, i5 750, and 4GB RAM yet only after 3 instances I get 85%+- physical ram percentage which causes alot of crashes to some of the clients