as far as cubase is concerned there is little difference between them, the 2600 will work fine without any software, just as the 5000 would. If you get the 5000 look for a style converter and initial floppy to be supplied, if the 2600 an applications and driver cd.
5000 pros, more on board styles (lots of downloads from Gunnar Jonny's site), built like a tank, better keyboard (if not hammered by now), great sounding amp/speakers, hardly need monitors, colour screen, more panel memories, 20 patterns in flash memory don't need loading, after touch.
5000 cons, floppy takes a long time to load/save, 3 part accomp.
2600 pros, more modern styles and latest styles on SD download, faster load/save, 8 part accomp, better pads, General Midi 2, digital audio recording through usb, digital audio playback from SD card if you buy an extra cost kit to transfer audio from the pc to the card.
2600 cons, cheaper lightweight construction, key feel not as nice, weedy speakers but fine with eq tweaked up through monitors, blue screen, only 24 panel memories (though a fast SD load partly compensates), no after touch.
...swings and roundabouts!
[This message has been edited by technicsplayer (edited 11-24-2005).]