First...go to HELP menu, type Network Wizard and read the info under the Start The Network Wizard topic.
1. Connect everything properly...cable modem to router, computer to router.
2. Run Network Wizard on XP. When asked how you connect, choose "residential gateway" because the router is a residential gateway.
3. Configure other computers, using the exact same workgroup name for all computers.
4. Double-check (eyeball) to verify that each computer has same protocols set up. Right-click on the network connection (each computer), right-click Properties, look at screen and verify that all are same for each computer. You might also have to enable NWLink Net BIOS as a protocol (I must do this on my home network), but let's assume that you won't.
5. Go to My Computer, right-click on each drive/partition that you want to share...and properly select such for sharing. If you want to share Docs&Settings folders, you might also have to select them individually (I do, but this just may be my quirk) but don't assume so.
Your systems will reboot after completion of the Network Wizard, so select drives for sharing after the system reboots.
That's it, in a nutshell