I don't think I can offer much consolation but this is how I see your situation.
I'm not exactly sure what you mean by 'notes' but if you read the following perhaps you can relate it to your situation.
If by notes you mean drafts, time machine were it working could have recaptured them. If you were trying to set up Time Machine using the internal HD that is not good practice. You really need an external HD of at least 500GB. They are not that expensive and for future security you should try to sort it.
If the notes were in Pages, Time Machine would not recapture them. I see you are in 10.6.7 Snow Leopard, and you would need to be in Lion or Mountain Lion to take advantage of the new system for saving of Pages. Incidentally, you really should update to 10.6.8 via the combo update.
If not at this moment, hopefully this will aid you in the future.
Ah, thats it. Never felt the need to investigate notes or the need for them, indeed, I'd forgoten about their existence.
Glad you updated; had you also done the combo I sent you plus the security add ons via Software update? By the way, I've since learned that Time Machine may not have recovered them either, although that's no reason for not installing it.
But as far as your notes are concerned, the only other location was MobileMe but as you haven't used that, I think the answer to your post is ... you've lost them. Sorry.