iMac MIDI set-up

[Tom Dempsey]

I am returning to music and sound production after a long time. I was 
involved in music production in the pre-digital era.
My current set-up is:

Yamaha PSR 225 keyboard
G3 iBook running MacOS 9.2
midisport 1x1 USB interface
Cubasis VST

I have a new 17" iMac running OS 10.2.6 and I would like to do MIDI 
work with it. A big problem is that Cubasis VST is MacOS 9 only and 
won't run in Classic. I recently used Cubasis with my iBook to provide 
music in a small theater production and I found Cubasis to be a little 
jittery in that during rehearsals it would never play the same song the 
same way twice in a row. It always sounded different.

  A friend suggested trying out Deck 3.5 on the 14 day free trial basis 
which I would like to do. Before I download the trial version I would 
like to ask if anyone on the list can tell me what else I'm going to 
need to try out Deck 3.5. Will I still need the USB interface or are 
there alternatives? Are there special cables I will need? Will the MIDI 
keyboard plug directly into the iMac? What internal software will I 
need in addition to Deck what Apple provides. Is OMS which I use in 
MacOS 9.2 needed in MacOS 10.2.6? What is the MIDI set-up supposed to 
look like?

Is Deck 3.5 something I should be trying out? Are there alternatives 
better suited to MIDI work?

Any advice would be appreciated.

Tom in Skopelos Greece