I was having the same problem, and was already using the PowerStore grid, but it was still too big for the content size that I had. The PowerStore grid shows 8 images across, and they were getting cut off.
I read all the posts here, and was concerned about the issue of resizing all the thumbnail images, which really wouldn't be convienent when you are adding images all the time.
I changed that to...
...and everything worked perfectly!!! No tweaks to CSS, one simple change!
Hope that helps others.