I am also facing similar problem
I have already have a XP-Pro and Win98 machines connected as workgroup 'SHANTIHOME'. Now I got another XP-Home laptop. I don't know it already have a workgroup name WORKGROUP. However I tried to add this new XP-Home machine to the existing workgroup 'SHANTIHOME', but in vain. My trials and their results are as follows
Preamble: Before doing the following things, the network environment is as follows
1. I could see both 'SHANTIHOME' and 'WORKGROUP' Microsoft Networks in Network Neighborhood
2. From the new WORKGROUP machine I could access the shared folders of machines of SHANTIHOME
3. If try to access the new WORKGORUP machine from any of the machines of SHANTIMOHAN, password is asked for. Though I have not set up any passwords, I could not connect to WORKGROUP machnie. This problem is same as all others facing. I suppose this is a either a bug or over enthusiastic security glitch similar to loosing the magic word 'open saseme'
4. I have no problem connecting to Internet through my DHCP wireless router connected to cable modem
My trials and results (I created a restore point before the trials and restored to this between each of the trials)
1. First I ran the Network setup wizard, and named my machine HP1 and workgroup to 'SHANTIHOME'. It changed the name of the workgroup to which the HP1 is connected to SHANTIHOME. But after reboot, **I couldn't connect to Internet**
2. Second, I restored to the Restore Point and changed the Wrokgroup name from WORKGROUP to SHANTIHOME. But again I lost internet access and still the HP1 machine doesn't show up on other machines
3. Third, I copied the Network setup floppy prepared some time ago to a CD (as my new HP machine doesn't have a floppy drive). Then I ran the program on this CD. The program warned that it will be running the Network setup program on XP and the store is same as that in (1) above
Since none worked to hook my new machine to the existing workgorup, I just resigned to useing two workgroups
But as it happened many times with Microsoft programs, a miracle did happen. Just to satisfy my soul, I tried changing the workgroup name to 'SHANTIHOME' again. Va, Va, Voom, IT WORKED THIS TIME. Yes, my new machine is now part of my existing workgroup 'SHANTIHOME'. Now date is about to change from Dec 26 to 27 ET. I hope this remains true when I restart all my machines tomorrow morning
Cheers
Shanti