Just because your assemblies are GAC'ed does not mean that they automatically appear in the .NET tab of "Add Reference" in Visual Studio 2003/2005. You can make your assemblies appear here by a registry tweak. First, decide which directory you want to store your assemblies. For example, say your projects copy the built assemblies to d:\build\output

Open the registry editor and navigate to the key HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\.NETFramework\AssemblyFolders

Create a new key beneath AssemblyFolders. The name is arbitrary, so give it a name that applies to the assemblies in the directory, perhaps "INITECH UI 1.0" Next, single click this new key, and in the right pane you'll see (Default) with no value. Set the default value to your directory, d:\build\output

Here's a screenshot of what this looks like for the already-present "SQL Server Assemblies" on my machine.

Also note that this can be set on a per-user basis by performing the same action in the HKCU hive, specifically HKEY_CURRENT_USER\SOFTWARE\Microsoft\.NETFramework\AssemblyFolders

If you want multiple directories, create multiple keys.

[Add standard registry disclaimer here] Back up your registry before making changes if you're not used to editing the registry directly.