right click on your desktop and select poperties. Goto settings. It will say "Display:" followed by the monitor and graphics card. Mine says "Samsung Syncmaster(m)s 700 (CGE7507*) on Voodoo3 AGP. I have a Samsung SyncMaster 700s for a monitor and a Voodoo3 2000 AGP for a graphics card.
If it does not say enough thee you can goto advanced and click on addaptor. You can also click start/setings/conrol pannel/system/device manager/display addaptor and see what is there. Mine says "3dfx Voodoo3"... 3dfx is the manufacturer.
With that, we can tell you your system will pobably need a new vidio card and depending on how old your system is, a new CPU also.
AMD Phenom II x4 945 3Ghz | ASUS M4A77TD | 2X WD 1TB SATA 2 hard drive | 2x2GB Corsair XMS3 | nVidia GeForce 8800 GTS | ATI TV Wonder Theater Pro 550 | Antec P-160 case | Antec 650w Earth Watts | LG Blu-ray Super Drive | LG DVD RW | Windows 7 Pro