Game port is usually integrated on the soubd card. Having assembled dozens PC for friends and upgraded my home PCs countless times, I've never heard of "gamecards".
;-)
Any way, R/C forum isn't, probably, the best pace to ask PC upgrade questions. Search the Net, there are plenty sources describing PC upgrades in details. Lokk, for eample, here:
http://arstechnica.com/guide/building/

Regarding the video card. "g-force 64mb cards for $90" isn't a good definition of a video card. Amount of memory isn't a good indication of the card performance either, 64MB with a slow chip will be inferior to 32MB with a fast chip. Get yourself a refurbisged GeForce2 or GeForce3 from NewEgg:
http://www.newegg.com/app/manufactor...Type=Refurbish
For example, GeForce2 GTS, which is faster than any GeForce MX card, can be bought for $55 there.

Have fun,
Boris