I recently tried out Windows Server 2008 x64, and I'm gradually transitioning. I'm installing all the tools I have on my XP drive, but I won't complete the switch until I've verified there are no blocking issues.
I regularly use Cropper to grab snapshots of my screens and portions of them. I tried running it, and it failed spectacularly! I decided to grab the code from CodePlex and see why it was failing. I ran through and was able to fix the issues. The main issue was that it was built against .Net 2.0 with Any CPU, but it depends on Win32 APIs. I switched the build configurations to x86, refactored an assembly load problem buried in a static constructor, modified the MSI setup project, and it started working.
I've submitted a patch back to the CodePlex project, so if you need Cropper on x64 Vista or Server08, you can grab the code with TortoiseSVN, apply the patch and make your own build. I've sent Brian a note, so I'm hoping he'll either add me to the project or apply the patch soon.
I used SvnBridge to pull down the source code. I didn't want to install Team Explorer JUST to pull down one project. I'm happy to report that SvnBridge 2.0 worked very well. I followed the instructions here for pulling down the source code with TortoiseSVN.