Renaming a file is big problem when you have lot and you had to rename them as you see. In Vista however when I was using the image previewer or the Photo gallery tool used to preview the images allows you to also rename it in the same window. This makes it very handy.
This place you also get to edit the image and even tags. So it can be a perfect managing tool on fly. Possible there are tools which can do that but this in vista is very handy.
Related: How to reduce image size in batch