CRM

You can download it from here.

There has been a lot more added to the "V3C" update than just Vista compatibility, such as:
- Integration with the Office 2007 “Ribbon”
- Custom MAPI Store (no more PST file!)
- SQL Express Edition 2005 SP1
- Inclusion of all existing client hotfixes
- Windows Vista Support
- User Access Control
- GPO deployments
- Internet Explorer 7

You can read the general announcement here.

It looks like about 30 to 40 hot-fixes have been wrapped up into one nice downloadable package. If you have seen "Buffer Overflow detected!" or had trouble with IE 7, you'll want to apply this rollup.

Actually, I'd recommend applying the update even if you haven't seen those common errors.

Grab the update here.