A Miami-based system integrator that's selling an unauthorized Mac clone also is offering the open source Ubuntu Linux desktop as an option on the system, as well as Windows XP and Windows Vista.

Psystar also has introduced a new system called OpenPro. It's a beefed-up version of its Open Computer clone.

The company claims it will ship either with a choice of pre-installed operating systems that includes Ubuntu Linux 8.04, Windows Vista, Windows XP, or Apple's OS X 10.5 Leopard.

Ubuntu is free. Vista or XP costs an extra $150, while Leopard will set you back $155, according to Psystar's ever-evolving Web site.

Psystar's Internet store was closed Wednesday because, it said, its credit card processing system was down. The company appeared to be back in business as of Thursday.

Psystar claims its Mac clones cost about one-quarter of what Apple-branded systems go for. A company exec I spoke with, who identified himself only as Robert, accused Apple of artificially marking up the hardware on which Leopard rides by as much as 80%.

(I'm assuming 'Robert' is Roberto Pedraza, whom, along with one Rodolfo Pedraza, registered Psystar to do business in Florida, according to state records).

One version of Psystar's Open Computer features Apple's Leopard OS X 10.5 operating system ported onto generic PC hardware that includes an Intel Core 2 Duo processor at 2.66 GHz, a 250-GB hard drive, and an Nvidia GeForce 8600 GT graphics card.

The system is priced at $804.99. A similar, Apple-branded computer would cost more than $2,000.

Roberto, er, Robert, told me earlier this week that he believes Psystar is doing nothing illegal despite the fact that Apple's end-user license agreements explicitly forbid the installation or sale of its operating systems on third-party hardware.

Robert implied Psystar would be willing to try its luck against Apple in court.

Still, Psystar changed the name of its Mac clone from OpenMac to Open Computer earlier this week -- perhaps in response to anticipated legal pressure from Apple. "The name 'Open' has been selected to reflect the fact that ANY consumer operating system can be installed and run on it," said Psystar.

More on Psystar here.