Computer not accessible over network

A simple enough problem this time. My mind has turned to mush. Maybe because I am still at the office …

I have connected 2 computers to the hub. They are both on the same workgroup. Both are windows XP Pro .. (blech) … Folders are shared. But when I try to access them I get a computername not accessible error.

I have tried enabling local user access from the registry. Turned XP firewall off for both computers.

Help !!!

Thanks in advance