Back to the OP: If your DAW isn't equipped with a virtual keyboard like Logic, I would seriously consider investing in a MIDI keyboard. You can usually find one for a steal on ebay. You don't need anything fancy, so you can probably pick one up from around $50 - $75. Though it's by no means necessary, it will certainly speed up your workflow.
I can recommend the LPK25 keyboard. It's simple enough for playing and putting in notes and the keyboard itself is not bad (but it's hardly professional either!). The arpeggiator is very fun to use for trying out arranging and so on and for the price and size, it's a bargain if all you want is to put notes in your DAW.
One problem I have had with it is the micro USB connector on the left side of it is a bit wobbly and occasionally the connection will break and disconnect from your PC/Mac. This breaks up my work flow as I then have to save my work, close my DAW, check the connection and then restart my DAW. This has been better since I moved the USB cable and left lots of room for the cable to flex so this is easily solved.