Moving to Team Foundation Server
The process went reasonabily smooth from my perspective (largely due to the fact the Jeremy did all of the work while I was away on holiday :-) )
We did however, encounter two mostly unexplained problems post-migration that are worth mentioning.
Although I don't actually understand the cause of the problems, as we've found solutions that worked for us I figured it might be useful to somebody if I post them:
The first type of problem we've had, repeated over several projects and solutions is that for some reasons VS would fail to find a project file in a folder althoguh it clearly exists in the path specified in the error message. because the project cannot be found it from VS perspecive it appears as unloaded in the solution explorer and we could not build properly.
As we could succesfully add the project to another solution we realised the problem is not in the project itself, but scanning the solution file we did not spot anything useful.
The problem was solved by deleting the .sou file created for this solution and letting TFS (or VS) re-generate it.
The second problem we've had is that when we tried to build a project on one of the machines (mine, incidently) we'd get an access denied error when VS tried to create assemblyInfo.cs.
I'm not sure why it tried to re-create it when one already existed, or why the case of the file already existing is not handled, this has to be a bug in VS, but deleting the file and letting VS re-create it solved this problem as well.
far from being the discoveries of the century, but hopefully someone will find this post useful. I'm sure I will a few weeks from now when I encounter this again and forget what it was that I did to solve it!