DEAR,
If you are having so big problem you must first have base knowledge on LINUX. On start I had also problems But then comes up new things. You must first know the think. Also when you build computer you had problems. But When you have all in hand is simply the best as LIONSTRACS MS x76 (for me) I'm playing with it on performance. I can tell you that it sounds fantastic. Also I had no problem with loading Big PIANO NI KONTAKT is fine tool. You can put inside piano of 800 MB with no problems of loading. When you push key is rights tone played. But you must understand system. In this moment is possible to put inside 4 GB RAM This is enough for all your playing all night long. Also keyboard is developing. Every day new things on web. (LIONSTRACS & LINUX) This is full functionality.
I thing CRAIGH you must check once more LIONSTRACS MEDIASTATION X76 but FULL VERSION WITH COMLETE NEW SOUNDS
Abacus BILL
SORRY but WERSI: You can check on:
http://www.mercy-no-wersi.com/ I'm glade that I find so good and reliable thing.
LIONSTRACS X76 is much better then standard keyboards without possibility to upgrade on what you want.