Can I get some advice on a NOOB Concrete5 issue?

I'm testing Concrete with XAMPP Lite on my local Windows box. My site and theme are all running well on my localhost, but when viewing it from other boxes on the network, the web browser isn't displaying the images located in /themes/<mytheme>/img directory. These are background images that appear in the header (a logo and mouse-over button highlight images).

Read permissions are setup for Everybody in these directories. I can also drill down from the browser directly to the image and see it fine (i.e.http://<myhost>/concrete/themes/loadfoov2/img/myimage.jpg)... so it doesn't seem like a permissions issue.

Any advice on what to check where? I'm guessing that maybe this is more of a XAMPP issue than C5? It doesn't matter which browser I use. The result is the same.

Anyway, thanks for any tips.