You should set the crop function in the addon.
This will crop all images to the same size (if the images are larger than the given width/height).

Edit the block
Open tab Image settings
Add the max width of the thumbnails
Check the crop thumbnail checkbox.

This should do the trick.

(Clear the cache of C5 and your browser if you don't see any changes)

Thanks for the quick reply, I played around with the crop function before posting, it doesn't really have the effect I desire.

Take these two images for example:
http://www.awesomedesigner.com/img/folio/5.jpg...
http://www.awesomedesigner.com/img/folio/1.jpg...

In the first one cropping it would make the whole picture awkward, you can't even tell what the picture really is. This is where a custom thumbnail would work great:
http://www.awesomedesigner.com/img/folio/t/5.jpg...

In the second once you crop the picture the title text is missing or cut off. Once again a custom thumbnail would work perfect:http://www.awesomedesigner.com/img/folio/t/1.jpg...

Thoughts? I have some .php and .js experience if you wouldn't mind pointing me in the right direction.

I see your point....

This isn't an easy thing to do.
For this function we have to edit the addon and add the possibility to select an additional thumbnail for each image.

For now I don't see to many obstacles. Just another image selection I guess.

Right now I don't have much time to change this. But maybe we can help each other. Do you think you could change the addon with my guidance?

I'm up for the challenge. This feature would make my week and I'm willing to put in the time and effort. If it would be easier you can email me at "andrew@awesomedesigner.com"

Thanks again.