You could get Reaper, there is a free trial version
and get a somewhat decent (midi) keyboard....you won't be needing sounds from your keyboard, they can just be software sounds...takes some study of Reaper to get started, but once you're started anything is possible, the sky is the limit
there are samples and sounds out there on the net, or you can by a copy of Computer Magazine (CM), the disc on the magazine usually is containing a load of samples and things to play with
if you have specific questions about how to get started with a set up with for instance Reaper, there are many people out here who can help, and of cause, You tube tutorials and tips
good luck