I haven't got Vista installed, but a friend of mine does, and he seems unable to make aircraft.cfg edits with notepad as well.
This must be terribly important with Vista.
In the old days, we used to use computers so we could write things down. Before that, we used paper and pen, but the ink was messy.
Computers were a vast improvement over pen and paper, you could make edits in your documents with no erasing and pencil sharpening and Notepad was simplicity in itself, perfect for aircraft.cfg edits and so on.
Vista is just another improvement with computers, obviously eliminating the need to do anything anymore, it simply won't let you.
Just trust M'soft, it'll all be ok

Seriously, I don't know what the solution is, keep us posted when you find out though.
I actually had to make the edits for my Vista challenged friend on my PC using XP, then I emailed him the modified aircraft.cfg so he could carry on as usual 8-)

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