How accurate are the computer pronunciations?
I'm a native speaker of German and worked through most of the German lessons (mainly to give feedback and to get a feel for the general quality of the learning units). At least the German computer voice is pretty good, though it has its glitches, of course. IMHO it's completely fine for beginners and intermediate learners. If you're in doubt about some pronunciations, you can go to http://www.forvo.com They have recorded voices of native speakers for a lot of words. You can even explore regional differences.