Currently i am considering image resizing with ASP.Net. I have two choices, one is resizing image on the fly when displaying list of images. Another is when uploading image, make the thumbnails, store in harddisk and display the thumbnails when listing. Prior seems take more CPU time but less space while latter seems to be reverse.
Well, it depends on how the site is going to be used. If you expect heavy traffic on the site then I would say hard drive space is cheaper then CPU power.
If your site is light traffic and only a few pictures, then I would ask you why you would want to go to all the work to program something to make thumbnails on the fly.
The only case where I would use the on the fly method would be if the site gets light traffic and has a huge ammount of pictures. *The point where it would be more efficient to make the program than the make all the thumnails.*