Mike, all,
I've tried to download a 30 day full trial so far of CS4,
Every attempt so far gets a 200k downloader/installer of the
larger ~500-800Mb file but nothing happens when I run it.

It was from the Adobe site and also a mirror reputable software
site.
Can anyone recommend a version or download site that gives
me a play with simple layering tyechniques in 16bit files.
It doesn't have to be the latest version.
Masks, deconvolves etc that Ken Crawford describes on his site.
That sort of stuff.....
cheers,
Sorry for the OT post again Mike