Hackers defaced the home page of the Oregon University System, posting a caustic message telling President Barack Obama to mind his own business and stop talking about the disputed Iranian election.

Attempts to access the university system’s Web site were automatically redirected to another page, where readers viewed a message said to be from Iran that asserted there was no cheating in the election. That message was up for 90 minutes before university system technicians intervened Wednesday morning.

The hackers apparently took advantage of third-party software that had not been properly updated, university system spokeswoman Diane Saunders said. Hackers frequently attack the system’s computers, but technicians usually beat back their efforts, she said.

Guy Kawasaki — a Silicon Valley venture capitalist who was partially responsible for marketing the Macintosh in 1984 — has almost 140,000 Twitter followers. Many of those followers likely thought it was strange that Kawasaki was suddenly into shilling porn, when a link purporting to host a pornographic video of “Gossip Girl” star Leighton Meester appeared on June 23. Anyone who downloaded the video discovered a virus that ravaged both PCs and Macs.

Antivirus organization Sophos posted a YouTube video explaining how the attack worked. As the Sophos video shows, the attack affected Macs. It can be taken for granted that the malware also infected PCs, because, well, everything infects PCs.

The malicious link has been disabled and no longer prompts visitors to download viruses.

Microsoft Corp. said Thursday that prices for the Windows 7 computer operating system are largely in line with those for Vista, and that consumers who buy PCs before the new system goes on sale in October will get free upgrades.

To drum up demand among people who aren’t in the market for a new PC, Microsoft also said it is taking limited pre-orders for Windows 7, selling some for as little as $50.

Microsoft will sell the standard home-user version of its new Windows 7 operating system for 8 percent less than the comparable version of its Vista system, as the global downturn hits spending on technology.

Windows 7 is Microsoft’s first new operating system in almost three years. With Vista, Microsoft made under-the-hood technical changes that left other software companies and device makers scrambling to make their products work with new computers. Many didn’t work at Vista’s January 2007 launch; people also complained the new system was sluggish.

Microsoft is promising a smoother launch for Windows 7, in part because it’s not a radical departure from Vista.

People who have tested near-final versions say Windows 7 boots and runs faster and spends less time nagging the user with alerts and pop-up windows than Vista does. It also tries to make it easier for people to navigate to frequently used Web sites, documents and tasks.