I found that using this URL was the only way to access the printer on the Windows XP Box:

smb://<your short name on the mac>:<your password on the mac>@<your pc workgroup name>/<name of the XP machine>/<shared name of the printer on the XP machine>.

So my smb URI looks like this:
smb://akirwan:<hml>@WORKGROUP/mike/hpdeskjet

This worked for me!

thanks akirwan...i registered just to thank you!!!

regs,
Nathan

Your tip almost worked. Your said to enter in Device URI--smb://<your short name on the mac>:<your password on the mac>@<your pc workgroup name>/<name of the XP machine>/<shared name of the printer on the XP machine>. So your smb URI looks like this: smb://akirwan:<hml>@WORKGROUP/mike/hpdeskjet

Alternate Solution:
We have an Epson Stylus Photo 1280 in our office network connected via USB to Windows XP PC that has not joined the domain, but as WORKGROUP. Only the computers in this subnet can access this printer. To print from MAC 10.3, we followed your hint, except that it did not work as the "computer name" would not get resolved and causing error connecting.... so, we used the Windows XP's static IP address assigned to it in place. Now our Mac OSX users in our Windows domain can print to a Windows XP Workgroup PC. (Without Appletalk protocol installed in XP). Therefore the alternate URI entry is: smb//polly:<password>@WORKGROUP/10.5.23.10/Stylus1280.