sometimes, the magic command used to integrate WinMerge as the Diff Viewer for TortoiseSVN gets lost. I aways forget what that command is so I am documenting it here (so I don't have to look it up again):

 

TortoiseSVN -> Settings -> External Programs -> Diff Viewer

 

Click "External" and enter the following (adjusted with your path to WinMerge, if necessary):

 

C:\Program Files (x86)\WinMerge\WinMergeU.exe -e -x -ub -dl %bname -dr %yname %base %mine

 

If you want this automatically setup for you. Install WinMerge AFTER you install TortoiseSVN and check the box that says integrate with TortoiseSVN.

 

I feel better already...