Only a few days after successfully suing Microsoft for $105.8 million, VirnetX has hauled the software giant back into court over the same two VPN-related patents (6,502,135 and 7,188,180). Expanding on its previous suit, VirnetX claims that its technology was used illegally in Windows 7 and Windows Server 2008. The prior case covered Windows XP and Vista, along with Office and services like Windows Messenger.

Microsoft is standing its ground, contesting that it hasn't infringed upon either patent. The company plans to appeal the original $105.75 million verdict, as well as defend against the new case. It also still faces the possibility of paying as much as triple the original penalty, because it was found guilty of willful patent infringement.

Redmond has described the ruling as "legally and factually unsupported." The company has petitioned the USPTO to re-examine VirnetX's patents -- and that's looking hopeful. In a preliminary review, the agency deemed all but three of VirnetX's claims invalid. That doesn't guarantee the patents will be tossed out, but it's positive sign nonetheless.

There's no word on exactly how much VirnetX is seeking in damages in the second case, but it sought $242 million the first time around. In a statement yesterday, VirnetX CEO Kendall Larsen said the latest suit is a "tactical and procedural post-trial action to ensure and protect our property rights as we proceed to final resolution with Microsoft."