If you live in New York, you owe it to yourself to go to SamAsh or some other music store that has DAW software running to experiencing it first-hand.
What's been recommended so far are all stellar applications and very strongly supported. Only you can best determine what your needs will be and which piece of software feels right to you.
The best thing to do is to check out the links thoroughly and to read the overviews, feature lists, and FAQs. Chances are a lot of your questions have been answered in these documents. The feature lists are very clearly listed on the respective sites for each of these products.
For more specific info, you shouldn't hesitate to call the companies or visit a music store to ask more specific questions and to see the software in action.
While there are many people who use PCs here for one purpose or another, I'd say that most people on this particular forum are Mac users. You may want to also check the forums of PC-based DAWs to determine what the system requirements are for your hardware as well as the feature sets of each.
Now, if you want to get a Mac and DP, you've come to the right place.
However, the most important thing is how any of these DAWs look and feel for you. This is something only you can decide.
It doesn't sound as if Pro Tools is the right choice.
Most of these DAWs have notation capabilities, although integrated notation is not always the best. Something like Finale or Sibelius will give you much more professional results should you find the notation features within any of the DAWs is not adequate. DAW notation has often been a weak points in general, but companies are working to improve this.
Composing *is* part of the purpose of any of these DAWs. Some products focus more on mixing audio. Some products might focus more on using virtual instruments. Which ones have the right balance for you? That's a hard question until you've tried them because not every piece of software appeals to every user.
Virtual instruments are supported by the major DAWs in a variety of compatible formats. These help greatly with creating audio performances of your compositions.
One website that may be very helpful is this:
http://www.tweakheadz.com/tweaking_your ... puter.html
It explains many aspects of building a computer based work station from A to Z.
Good luck!
