I used Irfanview for batch resizing for the web for a long while, until I realized that the resized files were much larger in file size than when I resized them and stored them at the same compression in Paint Shop Pro. It was disappointing because the batch processing was very nice, and I'm still looking for a program that will do it well.

Does ACDSee do it, Andy?

ps-oh, and I never used Irfanview for a viewer, so I don't know how it works for that.