You can download and install an image editing program like Irfanview, and then it is fairly straightforward.
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Open the image you want to resize (with Irfanview)
If you don't want to resize the whole picture, highlight the section you want resized. You can keep an eye up the top on how many pixels your selection is. If you want a square like 60x60 then you are best to highlight a square eg 220x220.
Go to the edit menu and crop the selection (Ctrl+Y)
Go to the image menu and resize/resample (Ctrl+R)- leave preserve aspect ratio ticked, enter a new width or height eg 60 pixels, and click OK.
[/list=1]Simple eh? You can skip the second two steps if you want to resize the entire image.
Thanks Rowan! I forgot to go back and answer the question. I use Canon ZoomBrowser EX (which came with my camera), and Macromedia Fireworks MX, which is way better.