Check out this free and easily used program. http://www.irfanview.com/
Once downloaded and installed, simply select file, then open your file, select image then resize, select the 640 x 480 pixels, click okay, then go to file and select save.
if that program is like the ones I have used, you might want to make copies to resize or rename them via save as when you resize them. Other wise, you may resize your originals
The xp toys re-sizer gives you the option of re-sizing the originals or making a small copy. If you don't click on the 'advanced' link you get the original and a small copy.
Yes indeed, if you resize your image and want to retain the original size image in addition to the smaller more manageable image, then when you save it, retain the original label and add something like "resized" or "2" on the end of the original label. Or rename it something else.
And thanks to Mange for the resizing (at work I'm on a T1? line; at home I'm on dial-up). Once I get my taxes settled (ouch!!), I might treat myself to a new computer & DSL, or maybe cable connection.