I think that is part of my problem - I can *sing* the scales - but can't "hear" them.

Same here, MMario. It's easy enough to sing: "1, 2, 3,..." because I've already heard the scale, and I know how it's supposed to sound.

But ask me to sing with flats and sharps mixed in, or worse yet, sing something like: "1, 5, 3, 7, 2, 6, 8," and I get lost. I can sing the first note okay (if it is in fact, middle C), but I can't jump from that to E with any accuracy -- until I hear someone sing it, then I can sing it back.

I have a voice-to-midi program called Akoff Music Composer, and it's pretty good... I don't have perfect picth, and so I slide around the notes a lot, and if I breathe on the microphone wrong, that registers as extra notes, too... but then I convert the .wav to midi, import the midi to Noteworthy, and then edit out all the notes I don't want, and tweak the pitches and timing, etc.

One neat thing about Akoff: it shows a mini piano keyboard at the bottom, and as you sing a note, the corresponding key on the piano flashes green. It's humiliating, sometimes, when I'm reminded just how off my singing is -- when it turns out I'm not singing the note I think I am. But if I took the time to really practice with it, my pitch would very likely improve.