What you could do is buy an audio interfaceand get the small version of Ableton Live. It comes with it, it's yours to keep and use. Not a demo.
An audio interface you could check out like at Sweetwater. And they help you hook it up right.
I use M-audio. For my midi keyboard, my bx8 d2 monitors and my audio interface. They are on the cheaper side but still very good.
I also have
Ableton Live 8 Suite. It's pretty cool but abo8ut the oonly part I like out of the "Suite" version is the vocoder (which is badass) and Sampler. I also like Electric though cuz it does the cool keyboard stuff like an electric piano.
But look around at Audio interfaces. Many of them come with Ableton Live. You can play it on your keyboard too. The Midi nots on your you know mouse and keyboard with you know like ABC's.
Ableton Live looks difficult to understand. But it isn't once you understand that each circle is simply just a way to adjust in a general way or anyway for that matter. You just have to learn where that section is like for audio and midi. Or fortuning you volume on a drum.
Abelton Live can have different screen backround colors which is pretty cool. but they are kinda funky so I don't usually use them.
Ableton Live is great for making music quickly and in a hurry. It's effects are very transparently clean and a little analog touch to them just right too.
You can always Upgrade it later for cheaper during some specials they have and they might come here pretty soon cuz they do it way later than their release.
Ableton live is a no frills no gills type of way of making music. It has a boring or colored screen and everything basically looks the same on it which is intimidating but not once you learn it from it helper dialog box. Oh yeh Info view was my best friend to learn with. Its in ableton and you can hide it with the triangle button. Or activate it back too.
Enjoy.