[Epson 7800 or 9800?]

The 9800 is a fantastic machine, However the HP5500 seems to be the Plotter of choice for Architects for many reasons.

Are you looking for a machine with an inbuilt RIP or external ?

[ESP Print Pro or other PS drivers]

Chris,

Yes indeed the HP5500 has replaced the 5000 however the engine has not changed, second user 5000 machines are sold complete with warranty and to be honest as good as the 5500 the only difference being a drying bar. once you have a new set of heads and cartridges you cant go wrong.

So a quicker machine complete with PS rip with warranty for the same money

[Trouble with HP800ps and OSX-color is too dark!!!]

You need to calibrate your plotter, and monitor, quite a simple process, I had mine done and what I see on screen is pretty much what I get out

[ESP Print Pro or other PS drivers]

Id suggest the purchase of a HP5000ps these can be sourced for a similar cost to the 500 and are obviously a better machine, complete with PS