You can also do it in Paint.
Just open it in Paint, go to Image > Attributes, and it will tell you the demensions that your picture is. (example: 1440 x 731 pixels)
Decide what size you want it. (say you want a width of 400 pixel)
Calculate what % of the original you want the final to be. In this case (400/1440)x100 = 27.8% (That's: Desired Width devided by Existing Width, multiplied by 100, equals %)
In Paint, hit Ctrl+A to select the whole picture.
Go to Image > Strectch/Skew
Enter 27.8 (your result) in the Horizontal AND Vetical fields. Click okay.
You now have a smaller picture with a big white border on the right and bottom. (The image shrinks, not the canvas size)
You can either click and drag the edges of the image to the edge of the picture, or you can go to Attributes and enter the demensions of the picture manually. (In this case, 27.8% of a 1440x731 pic would be ~400x203)
Kinda elaborate to explain, but for simple picture resizing, it's free. Once you do it a couple of times, it's fast.
Personally, I use Photoshop CS3.
