I’ve had a little playground TFS 2008 installation for a while for use with some “pet-projects”. I used TFS 2008 Workgroup Edition for this, as this is already part of MSDN subscription package. This edition works the same as the full one, but is limited to 5 users.

Now that I needed more user accounts for a larger project I tried to upgrade to TFS 2008 Standard Edition.

This seems to be pretty easy:

1.) Open Add/Remove Programs in control panel.
2.) Select “Visual Studio 2008 Team System – Team Foundation Server” and choose “Change”.

3.) At the TFS setup, select “Upgrade” and enter the new serial number.

4.) Finished.

(Summarized from Brian Harry's Weblog)

This is great, but unfortunately the serial number boxes are disabled / grayed out on my system (and all others as well) :-)

So it’s harder than expected…

But.. thanks to a thread in the MSDN Forums I found a way to change the serial number.

All you need to do (as step 0.) is open setup.sdb in
"Program Files\Microsoft Visual Studio 2008 Team Foundation Server\Microsoft Visual Studio 2008 Team Foundation Server - ENU"
and change the [Product Key] value (skip the dashes).

Voila!