I currently have a built-in Sis620 on my motherboard, and it sux. I bought a Gforce 7500 something, but there is no were in the motherboard to plug it in!!! help!!! there is no adaptor or anything, i guess ive wasted bout 700$ in vain...
Most likely you need a graphics card that uses a PCI slot. You can use a GeForce2 MX 200 or 400, or a GeForce4 MX 420. You can also use an ATI Radeon 7000. All will work fin. ATI will be releasing a card based on their R250 core. This will be like an MX version of their 8500 (full DX 8.1 capability, but only 2 pixel pipelines). It will likely be avaluable in PCI.
Those are most of your options unless you can grab an older card used. Even a nice Voodoo3 works great. I got one in my second machine (Duron 900Mhz) and it still runs great (at 800x600 resolution).