My son & I send music to each other at work. He's got XP, I've got X. I am on airport extreme and use Brickhouse. You have to make sure both programs are using the same port. I also made a custom filter on Brickhouse to allow incoming on that port. I have to initiate the connection to him as he cannot detect me. The first couple of versions tended to quit when sending files of more than a couple of megs. that's been fixed. My son sent me 250 songs at one time last week using 1.0.8. I just sent him the new version, the directions say 1.1.0 does not work with older versions. The developer is excellent about support. Naturally, if you are sending a mac file to a pc to ultimately be used on another mac, binhex it before sending or it ultimately won't work.