These are the current specifications for my computer system:

Processor:	Pentium III 866 Mhz
RAM:	256 MB PC133 SDRAM
Video Card:	3Dfx Voodoo 5 5500 AGP (64 MB texture RAM)
Primary CD-ROM:	TDK veloCD CR-RW 8x4x32
Secondary CD-ROM:	Generic 50x CD-ROM
Primary Hard Drive:	30 MB Maxtor 7200 rpm
Secondary Hard Drive:	20 MB Maxtor 7200 rpm
Mouse:	Microsoft Intellimouse Explorer Optical
Game Pad:	Hammerhead FX Dual-Analog
Monitor:	Sony Multiscan E200 17" flat-screen
Network Interface:	Generic 10BASET Ethetnet 10/100
Network Hub:	Kingston 5-port 10BASET

My system is quite capable of running as a non-dedicated server for most games for a small group of gamers (say, up to 10 people) without any significant performance loss.

My hub has an uplink port, so it can always be linked to another hub/switch to accomodate a larger group of gamers.