While I like how Windows XP handles copying/moving files to a folder with files that have the same names, I think there could be some improvements to how it handles moving picture files. Namely displaying resized previews, the dimensions, and the color depth. I just found out that KDE does this:

http://pokefor.greenchu.de/cutenews/data/upimages/KDE_CopyFile.png

Additionally, a "No to All" option would be nice.

Also regarding pictures, seeing options in paint to save a picture as either a 8bit, 24bit, or 32bit PNG would be nice. Additionally, seeing it save PNGs with a lowercase extension by default would also be nice.

Hopefully my suggestions will reach the Windows Longhorn team.