I had a similar problem with setting up my wireless network. The following
worked for me.
Make sure no firewalls are running on any of the workgroup computers. If so,
turn them off.
Make sure File and Print sharing is turned on for all computers.
If WEP is turned on, turn it off, at least initially. Once things are
running smoothly, you can then turn WEP back on.
Insure you have the current drivers for the wireless cards. In addition,
insure the most current firmware is installed on the router.
Make sure you use the same workgroup name on all computers.
Post back how it went.