Hyperlink'd .jpegs open in Explorer?

[JokeHeros]

I am trying to keep PowerPoint 2003 from opening up Windows Explorer when a
hyperlink to a .jpeg is clicked. They are high resolution diagrams (.jpeg),
and they come out blurry when Explorer minimizes them. Explorer gives the
option to zoom in (once) and the zoom is way too close.
The default setting in Windows is to use the "Windows Pic and Fax Viewer"
to open .jpegs, however PowerPoint always uses Explorer, and I couldn't find
any options to change this inside PowerPoint... any suggestions?

Thanks