I think I found a solution to your problem. When I recently got my macbook, I went crazy getting all kinds of new apps to test the power of this thing
One program I came across was
Audio Hijack Pro I got the trial version from versiontracker.com - don't know how long it last or what limitations there are, but I just tested it then, and it worked fine.
How it works: Once launched, it recognises all open apps. It took a bit of work to get it to record spoken text from textedit, but it DOES work. In Audio Hijack Pro, select the open app, and hit hijack (it may come up with a message saying you need to relaunch, do so - if you had to, hit hijack again) it's now in 'ready mode.' Hit record. It shouldn't record anything until it detects audio from the program, so you have time to switch to textedit, select the text and start it talking. Recording will then start, and be saved in the Music directory.
Files are small and quality is very nice. You don't need any cables or plugins at all. Just launch the apps and away you go. I'm sure you'd be able to figure out more advanced features if you need them - it's all pretty straight forward.
Good luck!