Using a custom compare tool in Team System
I'm a big fan of Beyond Compare as a general purpose file and folder comparison utility. I can't recommend it highly enough.
So of course I want to use Beyond Compare as my default file compare tool in Visual Studio Team System:

Here's how:
- In Visual Studio, select Tools, Options
- Expand the "Source Control" tree and select "Visual Studio Team Foundation Server"
- Click "Configure User Tools"
- Click "Add"
- Enter ".*" as the extension (eg, all files)
- Enter "C:\Program Files\Beyond Compare 2\BC2.exe" as the path
- Leave the params at the default of "%1 %2"
- Click OK
Works great! This is also documented, along with dozens of other source control systems, on the Using Beyond Compare with Version Control Systems page at Scooter Software as well. They recommend using params of "%1 %2 /title1=%6 /title2=%7", however.