Mind you the Eye-One is only a monitor calibration system. Their printer calibration system is a bit more expensive (around $700 IIRC).

I'm assuming, and maybe it's false, that if I'm looking at something on a calibrated monitor and send it to a professional printer, that I'll get out what I put in, so long as I'm not asking for colors outside of the printer's gamut. (And, maybe the professional printer service could give me ICC profiles for their printers so I could check for gamut issues before I ship them the bits.)