Hi John,
The problem is making more data. You need to interpolate between pixels to make the additional pixels. There are allot of ways to do it.
I resized this using Bicubic interpolation.

This one is 760 wide. If your target is a screen is 800X600 you need to allow room for scrollbars etc.
It's best to make your original images at least 4 times larger than their final size.
If you have any problems email me
Nbob@netopoly.net
Remove the N from the email address.