Easiest way is to re-size using the "paint" software installed in your computer.
Go to the "image" pull-down, and use the "stretch/skew" option to resize as a percentage (For example: 50% in both directions will shrink the picture to half size). Then re-save the picture and check the file size.
<font color="blue"> ( Easiest way is to re-size using the "paint" software installed in your computer. ) </font>
Only if you like to view postage stamp sized pictures.
You need to use a program that can perform compression on the image, not just resizing -- that way you can keep a decent sized image (640x480 or greater) and have the filesize under the 100K limit.
Microsoft's Image Resizer is probably the easiest way to go for someone who does not have a decent photo editing package (e.g. Photoshop) and has no desire to muck around too much with their images.