Aric,
That wasn't meant as a gotcha - not my place to do that.
I purchased Pimsleur's MSA (sp.?) awhile back and started in on it, but decided to defer until I can take some time off for an immersion course. I've got three years of Japanese, a pretty tough language, under my belt - and I could tell there was no way I was going to get Arabic "into my ear" only using the program.
Now if you have had, or can arrange, some other exposure to native speakers, that might not be a problem and my understanding is that both Pimsleur and Rosetta will do their part in building your vocab and grammar. But the sounds were just too alien to me, and my progress will be held up until that is rectified.
I tried posting an ad for a "conversation partner" on the bulletin board at a nearby mosque but no takers. I suppose they've had their fill of innocuous looking white guys who'd like to "talk".
One piece of advice: check Ebay for these titles - you should be able to save half.
Good luck!