I'll agree with most of the above and spell out my thoughts briefly and concisely:
1) You MUST make all machines XP Pro. XP Home will absolutely kill your whole system. I know, because I made this mistake for 1-1/2 years. This is the biggest and most important piece of advice. If you do nothing else, do this.
2) Cough up the money for a true server. P2P does in fact work. However, a server-client system gives WAY more stability of the system.
3) Make sure your computers are communicating through a Network Switch, NOT a Network Hub.
4) CAT 5e or CAt 6 cabling a must (CAT 6 is better).
5) make certain you have a Hardware firewall interfacing between your internet modem and your Network Switch.
Let us know how you make out.
