http://www.lotsageeks.com/?p=89 Really cool little tool. You rename the exe to the proportions of the file resize for example photoresize600.exe will resize to 600x600 photoresize400.exe will resize to 400x400 Then you just select all your images and drag and drop them onto the icon.
look for pixresizer in Google. It will do an entire directory at one time and let you choose the compression factor. Super freeware IMO.