I came in here to suggest the Canon MX860, but I see HardCore beat me to it. I got mine about two months ago after struggling with an old HP OfficeJet D135 for several years (damn those clogged print heads). Works really well, despite a somewhat confusing menu system. Prints are beautiful, scans are crisp (and the software lets you import them as PDFs, which is nice). Faxes and copies are, well, faxes and copies.
One thing I ran into with a Vonage line is if you set the voice quality too high the fax fails. Not sure if it is just me and my line, but I had the same problem with two different fax machines.