Audacity will probably do the job for you, but for transcriptions I'm not sure how it handles the pitch when the track is slowed down.
Logic will definitely be able to do what you want while keeping the original pitch intact, but I'm unsure you'd want to pay that much for what you require.
There are a few programs out there for transcribing, but I'm unaware as to how they work. Guitar Pro 5 is one of these programs, but when it comes to transcribing I'm not sure how it would work. I hope one of these programs helps
I can't say enough good things about this software....great transcribing tool, but the time-stretching algo is really good and you can just use it for that function alone. Set the speed and pitch independently, and export the file ... done.