Microsoft is, predictably, not all that impressed by Google's demonstration of its upcoming Chrome OS, but neither were a number of potential rivals in the Linux and instant-on operating system space.

Google released Chrome OS as open source on November 20. It did not, however, release a beta of the operating system for users, and said that hobbyists who would want to install it on their existing netbook or other hardware were out of luck.

However, developers can compile the source code and run Chrome OS in a virtual machine to test Web app compatibility, Google said.

Analysts note the ratcheting up of the rivalry between Google and Microsoft with Chrome OS's release to developers today, but the rival OS won't be available on new netbooks for another year -- and Microsoft seized upon that fact today.

"From what was shared, it appears to be in the early stages of development," a Microsoft spokeswoman said via e-mail.

"From our perspective, however, our customers are already voicing their approval of the way Windows 7 just works -- across the Web and on the desktop, and on all sizes and types of PCs -- purchasing twice as many units of Windows 7 as we've sold of any other operating system over a comparable time," the spokeswoman said.

Google is taking a longer term view, rethinking the OS and PC to achieve a better user experience, executives said today. For example, by dumping conventional BIOS-based boot-ups and only using solid-state drives , Chrome OS-based netbooks will be able to boot in 7 seconds, and run Web apps within another 3 seconds, the company said

That failed to impress Woody Hobbs, president and CEO of Phoenix Technologies Inc., a long-time BIOS software maker that has re-invented itself with a Linux-based instant-on OS called HyperSpace.

"Instant-on is about being able to access your Internet applications in 1 second. 7 seconds is too long," Hobbs said in an e-mail. "There is no such thing as 'cold boot' for today's mobile PCs such as netbooks and smartbooks. You should be able to use your netbook like you use your smartphone -- a press of a button and you are 'on'."

Mark Lee, CEO of DeviceVM, said Google's favoritism towards its own browser and Web apps could rub some users the wrong way, especially those outside of the United States.

"In China, users prefer Baidu, not Google," Lee said. DeviceVM's Splashtop platform boots into Firefox within seconds and uses Yahoo or Baidu as default search engines instead of Google.

He expects Splashtop to have been shipped on 100 million netbooks and other PCs by the end of next year, when the first Chrome OS netbooks are due to arrive.