Yeah, it makes sense, I did this exact same thing once
I did it by having one page which was my container and I passed everything to it via the URL. You'd check to see if the window was present, and create it if not.
Each thumbnail is in an <a> with associated href, so that those people without javascript enabled can still see the full images, just not in a fancy pop-up window. If the description is the images alt attribute then this will save even more time... You then don't need to clutter your markup and can just add event listeners and handle everything from script. It also degrades rather nicely for the small percentage of people without javascript enabled.)
What else? Oh yeah. Have location.replace('popuppage.html?img='+e.href); so they don't press back in your new window... Make it focus the popup window if it was blurred. Um. The popuppage would have an onload event which would handle resizing it to the correct dimensions and adding the description.
Now, I apologise for the long-winded and rambling description above of
one way you could tackle this problem. If you would like, I'd be happy to help actually do this with you, since I've got quite a bit of free time at the moment
