Cubase 4

Don't do it. Unless you need the new Plugin and Instrument gizmos (and I think third party stuff, even a lot of freeware is superior to those), the media bay (which proved rather usless for my daily work, ymmv).
No DX support, uses more ressources than SX3 (some older projects of mine run flawless on SX3, but to have them work hiccup-free in C4 I have to increase the latency), still some kinks to iron out (everybody and their mother is waiting for the long promised 4.1 update...).
The only thing I like about it is the draggable plugins. But that doesn't make up for the rest. I installed it but only used it for 2 songs so far.
The last 3 albums I recorded where SX3 again.
Just my 2cents, all the best.
 
That is just shity practices by Steinberg. From I read over on there forums they just dropped support without even warning users.