Mike is correct, the Repository module is released as a .net 1.1 module for use with DotNetNuke 3.X or 4.X.

HOWEVER, the source code is only compatible with .net 1.1 and therefore Visual Studio 2003. If you want to try converting the code to compile and run under Visual Studio 2005, you may certainly do so, but it will not be supported other than to answer generic VS 2005 and .net 2.0 questions.

Following is the only supported method for making code changes to the Repository version 3.1.10 source code until an official .net 2.0/VS2005 version of the Repository module is released.

IMPORTANT!: The source code is ONLY compatible with .NET 1.1, so you can only make code changes and recompile the source code using Visual Studio 2003. You can install the resulting package on a DotNetNuke 4.X site, but you must make any code changes on a 3.X site and rebuild the package.

PRE-REQS:
- DotNetNuke 3.X working web site
- Visual Studio 2003
- NANT Utility (http://nant.sourceforge.net/)

To make code changes:
1. Download and Install the Repository_3.01.10_Install.zip package
2. Test your local DotNetNuke 3.X web site, and test the Repository module
3. Download and Unzip the Repository_3.01.10_Source.zip package into your /DesktopModules/Repository folder
4. Load the /DesktopModules/Repository/DotNetNuke.Repository.sln solution file in Visual Studio 2003
5. Make your source code changes, compile and test
6. Make a final compile in Release mode
7. Exit Visual Studio 2003
8. run the /DesktopModules/Repository/DotNetNuke.Repository.build file

You will see 2 new packages in the /DesktopModules/Repository/packages folder, one named Repository_3.01.10_Install.zip and Repository_3.01.10_Source.zip

You can now take your recompiled install package, Repository_3.01.10_Install.zip and install it on your DotNetNuke 4.X web site.

Sanjay,

I have to comment here that this was the most helpful thread on modifying a module I have found.  I just spent two days trying to figure out how to adjust the Gallery and Forum modules and kept running into the use of the Module Upgrade Wizard and the notes about only being able to modify a module with Visual Studio 2003 and DNN 3.x.  This thread offers a third alternative that from my perspective was the easiest to implement.  Here's my take on the three solutions I ran into:

1) Use DNN 3.x and VS 2003 to modify .net 1.1 modules:  The supported way, works fine but you have to have 2003 installed as well as a DNN 3.x version. 
2) Sanjay's method detailed in this thread (basically just updating the vs2003 project to a vs2005 project):  The quickest way to acomplish a minor modification.  The result is not supported but in reality there is very little changed with the way the code is organized and therefore less risky than the 3rd option.
3) Upgrade Module Wizard:  Good if you are planning on a large scale or long term modification of the code base.  It also will require a significant amount of work and complete testing.

So just wanted to say thanks Sanjay.  As of tonight I finally have the modifications I started to do two days ago in place.

Ted