2k and XP won’t network.

I have an XPpro pc and a 2kpro pc connected to a small switch sharing a DSL connection. They are both workgroup machines. I have norton internet security on both machines. Both machines can access the internet simultaneously with no problem, BUT, I cannot get them to “see” eachother. I’ve tried disabling Norton internet security, but it had no affect. Any suggestions? Both pc’s are always logged on as administrator. Please let me know if more details are needed.

thanks