Windows 7 Utility to conditionally delete files with same name

I am a photographer and generate "raw" and JPG images. At a certain point in my workflow, I need to delete all the JPG images before proceeding. That's easy enough; in Windows Explorer, one can sort by type, then delete all the JPGs, or one could open up a command prompt in the directory and "erase *.jpg". But there's a complication; in some modes of the camera, no raw file is generated. In those cases, I just have one .jpg that I want to keep. Here is an example:

img1.cr2
img1.jpg
img2.cr2
img2.jpg
img3.jpg
img4.cr2
img4.jpg

I want to process this directory and end up with one file of each filename, as follows:

img1.cr2
img2.cr2
img3.jpg
img4.cr2

The pseudocode would go something like this:

Sort files by filename fname

IF fname.jpg and fname.cr2 both exist THEN delete fname.jpg

How can I easily do this? Thanks!

Dilip