can you type "smb:/" in konqueror address bar and press enter ..that will bring you to another window that will show a graphical representation of computers on your network ..you should be able to see different workgroups, click the one you have your computer under(mine says mshome) ..and your computer should show up ...clicking on the icon and you will see all folders you have set up to be shared on the network ..
notice that following the above will allow you to see the local folders you have set up to be shared as if you are looking at them from another computer ..if you can access them, then the problem could be on vista's side ...if you cant, then that might mean you havent set them up properly ..
vista can see the machine, it just cant access it and that could mean a permission issue ..make sure the folder you have set up to be shared have reading permission set