Two suggestions,
One, set you camera for the lowest file size which is 640 X 480, plenty good enough for 99% of your pictures (save computer space too) Then you won't have to do any resizing at all. More people should be doing this.
I hate oversized pictures. on forums, and in emails.
Another good program which is free and easy to use is, VCO image resizer. just select your picture, set width to 640, that's it. It creates copies by default, (but can also replace) in case you ever want an enlargement of the original.