I started to write this
Before I saw Tim's already gave a very good answer, but since I already wrote it
... here's it another way to try.
One of easiest to shrink them is to use Microsoft Paint is available in every version of windows
1- click on "Start"--> "All Programs"--> "Accessories"--> "Paint"
2- click "File" --->"Open" it will open in your "My Pictures " folder Note if you don't see it in that folder click on "My Computer" to find it.
3- click on the picture you want to resize then click on "Open"
4- once the picture is open click on "Image" --> "Stretch and Skew"
5- try adjusting the Horizontal and Vertical both equally try starting with around 50%
6- click on "Attributes" to check the size (Size on Disk) note: you can also resize it here if you like. goal is <100k
7- once you have the size you want click "OK"
8- click on -> File -->"Save-As" rename it to so you don't save over the original picture
