Need Simple Recording Setup Advice Options

[magician]

I've been out of the home recording loop for a few years (children, etc.), and am finally looking to start back with a simple setup. I'm Mac proficient and used to be proficient with Vision and Galaxy, but haven't touched any of it for years.

My goal is to do some songwriting and create simple demos.
I don't mind purchasing some additional software/hardware within reason (under $400?), but of course would prefer to use what I have, if even possible.

My main concern is I remember spending more time trying to get things to work together than actually creating, and don't want a steep learning curve. MIDI sequencing is probably fine for me and I'm comfortable with the process, unless digital audio is easier than I think. I do enjoy the process of MIDI sequence editing and massaging tracks into what I call art.

My tools?
PowerMac 7200/90 running OS 9.1(I prefer using this machine as it's not used for anything else and could be dedicated to the music setup)
iMac 800 Flatpanel running OSX 10.1.4
Roland SoundCanvas SC-880
Roland U-20 keyboard
Yamaha MD8 Multitrack MD recorder
Vision 3.01 (don't even know if it works with either OS)
Opcode Studio plus Two MIDI box (2 in, 6 out)
various outboard compressor/limiter, reverb, etc.

Where should I start?
Is there something new that I should be looking at that will make this easier for me?
Again, simplicity is the key, as I want to just sit down, hit record and play.
Thank you for any help or advice you can offer.