Hardware requirements
Of course, bigger, faster, BADDER is always the norm. Monster machines are great servers (+p300, +128ram) and you should have a bitchin' 3D card if you wanna play on the server at the same time.
Connection: You gotta have at least a cable or ISDN connection (WORKING 56k modems can barely support 2 clients).
Remember, it's not just ping that is involved with a good connection. There's RELIABILITY... having a server deliver intact packets, and not dropped ones, etc.
Some general rules of thumb:
10mhz of cpu per player.
3megs of ram per player.
(values not standard, I just pushed them up
a tad seeing as how SiN eats resources for lunch)
If you add it all up, you'll find you probably are well above the totals for an avg game, but take into account that your desktop uses quite a nice sum of memory and cpu processing, especially win95/98, and any other programs you run other than the server, takes up resources.
All this is just general knowledge... any wierd quirks can happen, a server can be laggy or fast for who knows what reason.