If you have MS office, you can use MS Ofice Picture Manager. If you don't, you can download "Paint.net" a free graphics editor, similar to adobe photoshop.
Using MSO Pic Mgr - Right click on a pic and "open with" MS Office Pic Mgr
Once open select "picture" in the menu bar. From the pull down menu select "resize". The different options will come up on the right.
If you're trying to make an avitar you might have to go to "picture" then "compress picture" to make the file size smaller. Hope that helps.
BTW anyone got a copy of Photoshop I can pirate?