I know exactly what you're looking for. There's two programs that come to mind:
Sibelius and
Finale. Each has it's pros and cons - i.e. Sibelius is more professional and has more features than Finale, but it's also more expensive. However, I'm not sure if either of them can write the letter names along with the notes on the staff, because I've never had to use a feature like that. If you have some trouble with reading music, here's a good guide to help you:
http://www.bauerstune.net/Notation/notenames.html
Here are links to the two programs I mentioned here. I must warn you, though, that programs like these are fairly expensive. Any free or trial versions of similar programs you find probably won't do the trick - sometimes you can't save your work, etc.
Sibelius: Sibelius - the leading music composition and notation software
Finale: Finale Music Composing & Notation Software
That should help you in your search for music notation software
EDIT: I think each company has international distributors if you don't live in the US or Canada. Browse through their websites.