Hi Lauren,
There is a big difference between words typed per minute and words transcribed per minute. If you have to stop and look up every word while you are transcribing your speed is going to suffer. That is why it is so important to learn as much as you can while you are in school. Regardless of your experience, there will always be some words you will have to look up, but the less you have to, the better your speed.
Getting your keyboarding speed up as high is possible is helpful, though don't forget that knowing what you are transcribing is just as important.
As far as Career Step, they have a good reputation and are approved by AHDI. You might check out the other approved schools on AHDI to see if there might be a better fit for you, as courses tend to cater to different learning styles. I would say that Career Step definitely has a lot of students. I would make sure the course included the AHDI Book of Style, either furnishing it as part of the course or you purchasing it and learning it on your own if you realize that transcription is the career for you. Most national companies use this as their style reference.
Try googling "Career Step transcription reviews" (no quotes) and you might get a good idea of the pros and cons. I believe they have an affiliation with some national transcription services as far as obtaining employment after the course.
I found this article of particular interest regarding transcription schools in general:
http://undress4success.com/medical-transcription-scam-alert/Hope this helps!