i have a mac os9.2 and a pc with windows xp and a pc with windows 2000.

i want to get a hub to connect all three to use the internet using my one cable modem. i was wondering will this work? are they all compatibile?

 

It depends on what you mean by compatible. All three of the operating systems can be configured to connect using TCP/IP, the protocol that the internet uses. You can use a hub to connect them to one modem using Ethernet cables. However you will either need to get an ip address from your ISP for each computer, or set up a way to share a single ip address between the three computers. Some cable modem service providers will sell you an additional IP (I used to do technical support for AT&T when I left them they were charging $5 a month for each ip, but that may have changed since I moved on). See if your ISP will give you any help with the network. Some will, some will not.
In the long run I think you want to purchase a simple router, not a hub. The router will be more expensive up front ($50-$90 at best buy, office max etc.) but cheaper in the long run, and easier to configure with the differing oses (xp and win2k get along pretty well together, but os9 gets testy with win stuff). But you defiantly can do it.

 

One way to share a single IP amongst multiple users is via a proxy server.

You can run something like WinProxy or other proxy server software on your gateway machine (the machine connected to the modem).

All machines on the network will then appear to be coming from a single IP address (that of the proxy). This saves you buying extra IP addresses, accounts for extra users etc.

Winproxy for one automates this entire process during install making it pretty much a no-brainer.

You'll still need the hub of course to network the other machines to the gateway and for your LAN.