NETWORK SPECS.
2003 Compaq Presario with Windows XP Pro
Home-built 350 MHz processor PC with Windows 98
Home-built 450 MHz processor PC with Windows 2000 Pro

All 3 are connected on a LAN with a Linksys LNE100TX Fast Ethernet Adapter and a Linksys router. I don't know if these are two different things or not, but I thought I'd mention both. The computers are supposed be able to see all drives and programs and the works of each other. A printer is directly hooked up to the Presario and the other computers should be able to use it through the LAN. Our Internet connection is through a Cable Modem. We use the latest free version of Zone Alarm

Here is the problem. It is complicated and confusing. The computers have the appropriate computers in their My Network Places folders. But the 450 can't actually see the other computers, nor can the others see the 450. The Presario can see everything it should in the 350, but the 350 can only see documents on the Presario. All 3 computers get Internet access though. Only the Presario can use the printer. Things seemed to be fine before we had the Presario and we had a home-built 800 MHz PC with Windows 98. We had to get the Presario because the hard drive in the 800 crashed. But I don't know if these event triggered the problem.

I hope this is enought info. I am new to network troubleshooting.