Here's how I do stuff like that: dir and Excel.
Go to the folder, shoot up a command prompt, type
dir *.jpg *.jpeg *.gif *.png > listing.txt (this will list all jpegs, gifs and pngs, piping the output into listing.txt)
Then open up Excel, drag in listing.txt, and go Data -> Text To Columns. Choose Fixed Width, and put a delimiter at the beginning of the file names, then hit Finish. Then delete everything except the filenames, and in column A write something like
<br><img src="; in the column after the filenames just write
">.
Then drag the bottom right blob on those cells to get them to fill the whole column...
Then copy back to Notepad. Voila - great HTML with guaranteed correct spelling, capitalisation, plus you get to decide exactly what goes either side of the image filenames!
Try it... it works!