First off, it is best to resize your pictures. I like to take my pictures in the highest resolution (size) possible for clarity, save those to my computer, and then you can do anything you want with them from there. Resizing them for posting helps the guys with slow internet connections because they load faster. Plus, the powers that be on this board have set a 250 KB size limit per post.
If you have Windows XP, ******CLICKY HERE*******. This will install the PowerToys Image Resizer. It's from Microsoft so its safe. Just agree to everything it says and you'll be cooking with gas in no time.