it will detect that you have all the other files ONLY if the batch you're downloading contains the same files you have.

But luckily for you, you dont need to do any of that. Just use a program like BitTornado of Bitlord, or utorrent. These programs allow you do specify which files you want to downlaod out of a batch file. Simply load up you batch torrent using one of these programs (or any other program with the same feature) and disable all the files except 150.

Edit: heh, i was just about to reference Kai's thread too