Windows 7 Tip: 
There are so many free online image resizer and editor in web, here is the new one My-I-Size. This is simple online tool lets you resize GIF, PNG and JPG Images online very easily and fast too.
In their own words:
MY-i-Size resize this image to the size you want and the best: it keeps the image quality and proportions! You just have to insert it in MY-i-Size, save in your PC the new resized image that MY-i-Size shows and insert in your e-mail / blog / forum / website, etc!
Features:
* Resize GIF, PNG and JPG images.
* Upload images from your PC or get them from URL.
* Dowbload images to your PC
The options are limited it seems…I will give it a try atleast.