KaranTh85: The proper thing to do would have been to post a link to the relevant e-VGA page and also give more info about the rest of your old computer.
Anyway, to give you an idea of what to expect: I know several people who are still happily gaming with an onboard GeForce4 MX with 32 or 64 MB allocated for display. They can play games like Warcraft, COD (not COD4) and the like at low settings with reasonable frame rates. The CPUs are AMD Athlon XPs in the 1800+ to 2400+ range (roughly equivalent to P4 2-2.8 GHz) with 256-512 MB RAM.
An FX5200 AGP is significantly faster than a GF4 MX, and 6200 is still faster. A PCI version will be slower, but should be quite useable.