I have been playing around with System.Drawing and System.Drawing.Imaging quite a bit in the past few days. I didn't quite know what to expect but the libraries are very powerful. I was able to take 250,000 images which were in the 320x240 format and resize them to a low res 256x192 and a high res 640x480 in about five hours. All the images were photographic quality and they look great in both of the new formats. I did, however, notice a very small amount of distortion in some of the images if a lot of sky was visible but I can't tell why they were distorted.
The libraries, like I said, are very powerful. I am very glad I didn't use a third party product to do the processing. If you haven't checked out System.Drawing.Imaging, all the codecs for different image types are in this library and they work wonderfully. Good job to the team that wrote these libraries. I guess this is common place for the framework but they are making all of our lives a lot easier.