Yamaha Disklavier and home studio

My husband has a Yamaha Disklavier. Before he got the Disklavier, he used to compose music all the time using Cakewalk and some other gear. A few years ago, he got a Tascam US-428 Midi board.

For Christmas this year, I'd like to get him a new computer and something else to encourage him to start composing again. I know he wants to hook the Disklavier to a computer. I already bought Finale, but what else should I get? He has an old sound module and the Disklavier has one built in. The Tascam comes with Cubasis VST audio recording/MIDI sequencing software, so I don't think he needs Cakewalk again. Recommendations on what else to get?

Any suggestions would be greatly appreciated.

Thanks.

Depends on what other gear he has. However a new computer, cubase and a mixer should be sufficient. A midi keyboard is probably one of the things he has, so the only thing he needs is a symphony orchestra.