This was a tricky puzzle to write. I got the idea for it on Monday, and spent a day and a half trying out board layouts until I found one that worked. At least, I hope it works. I did test both halves of the puzzle, but I worry that I missed an alternate solution to the Slitherlink portion. Ah well.
7/1/11: Blast it! The Scrabble set I was using was missing a letter, and consequently I only used 99 of the 100 tiles. I have edited the puzzle to take this missing tile into account, and uploaded new files.