Target Screen Resolution?

This is really dependant on your user base. If Microsoft tells you to develop for 1280x1024, but you're developing applications for everyday users, you're going to have a lot of angry customers (since 800x600 is still supported in Vista, and many users, particularly those with poor vision or smaller monitors, will continue to use 800x600). Similarly, if you're developing a CAD application for a bunch of mechanical engineers, they'll probably be upset if you don't use a 1600x1200 (or larger) screen to its fullest.

My guideline is always ensure a consumer application is usable at 800x600, and also that critical applications (e.g. virus scanners, recovery software) can be functional in 640x480 (in case of use in safe mode or use of VERY old monitor in recovery situations).

Hope this helps,
Josh Lindenmuth