The reason that you cannot see shares between the 2 workgroups is the master browser in one workgroup does not know about the other workgroup.
If you had a NT or 2000 domain, it would know about them.
So to be able to see all the systems, you will need to do one of the following:
Place all the systems in the same workgroup.
Stand up a domain and place all the systems in the domain.
Stand up a domain and let the PDC's Master Broswer keep up with the workgroups. This solution doesn't offer any additional security and doesn't take advantage of the capabilities of a domain.
A good explanation of the differences between workgroups and domains can be found here:
http://www.windowsitpro.com/Windows/Article/ArticleID/2501/2501.html