"Search and remove" software

I need a piece of software that can match 2 text files up against eachother, then remove all lines present in one of them from the other.
Lemme be more specific:
I have a fairly huge HOSTS file, and Im using a batch script to weed out the servers that are non-functioning. It dumps the non-functioning into a txt file. So I sit there with 2 files, and manual searching is just balls. And yes I do mean search and replace in notepad, it would take forever.
I used to have a batch script that would do this, but it didn't work prop.
Compare programs is just one small step up from the search and replace, still too much hassle.

So I hope you understand what Im after :)
TIA


//peace

i think piping your bad hosts file through find or edlin would work,
been a while, let me think about it more