Can u download Irfan view. It's been around for years and is a handy little program at times that I use exactly for this when the image doesn't need the full power, and long start time of a bigger program. It is also under a right mouse click in the Open With menu on Windows. Resizing is straight forward and by pixels or percent, and it does a good job without tearing up you image.
It will also open any RAW file I have ever thrown at it. And it is worth downloading the complete add-on pack and installing that.
http://www.irfanview.com/
Ha, just noticed Paul's post, so I am seconding his recommendation.