He also hinted that if Psystar proves its allegations, others may then be free to sell computers with already installed.

In an order signed on Friday, Judge William Alsup gave Psystar the go-ahead to amend its lawsuit against Apple. According to Alsup, Psystar may change that countersuit, which , to instead ague that Apple has stretched copyright laws by tying the Mac operating system to its hardware.

Alsup had in November 2008, but left the door open to a modified complaint. Psystar took advantage of the opportunity, and filed a revised lawsuit in mid-December. Apple, however, had hoped to quash Psystar's revision, saying that the Florida company "attempts to repackage its dismissed antitrust allegations under the guise of copyright misuse."

On Friday, Alsup said that Psystar could continue to press its once-dismissed case. "Psystar may well have a legitimate interest in establishing misuse [of copyright] independent of Apple's claims against it -- for example, to clarify the risks it confronts by marketing the products at issue in this case or others it may wish to develop," Alsup said in his ruling.

in July when it said Psystar broke copyright and software-licensing laws by selling -based computers with Mac OS X 10.5 preinstalled. equipped with Apple's operating system since April 2008.