Unfortunately, there are no PowerToys for Vista yet.
A few third-parties have written alternatives to the Image Resizer program in XP, but I have not personally tested any of them, so I will not recommend them.
However, there is a cool trick you can do, using stock Vista stuff:
In Vista, the easiest way to generate a smaller, resized image is to trick the e-mail program:
1. Double-click image you want to resize to open in default Vista image viewer (Windows Photo Gallery)
2. Click the "E-mail" toolbar icon.
3. Pick a size and click OK.
You don't even have to send the email to yourself (although you can if you want). Just right click the attachment in the new email and choose "Save As." Now you have a smaller version of the large image saved....then, just discard the e-mail. :-)
