Yeah, go to the XLN site, download the installer, register yourself with thew. You'll find a registration number on your account with Sonar. Pick you stuff and run the installer.
You don't need to pick everything straight away. If you know their is one kit you want and a midi pak, but you are not sure about the rest, just pick them. You can return to make a more educated decision after you had a play with it.
You get some examples of the midi paks with the install, that should help you pick them later