I think *\.svn\* works to exclude the svn directories from projects on Windows.
Another option is to configure Windows Explorer with "Do not show hidden files and folders", in the View tab of Folder Options (Tools > Folder Options). SlickEdit captures this setting when it starts, and honors it in displaying files and directories in most places, including files added to projects. Note that you need to restart SlickEdit if you change this setting.
Regards
John Hurst
Wellington, New Zealand