According to the authors of the Engineering Windows 7 blog, the engineering team responsible for faster boot times has timed a early version of the upcoming operating system fully boot in under 15 seconds.
Apparently it's a big focus over at Redmond and we say about time!
For a PC to boot fast a number of tasks need to be performed efficiently and with a high degree of parallelism.
• Files must be read into memory.
• System services need to be initialized.
• Devices need to be identified and started.
• The user's credentials need to be authenticated for login.
• The desktop needs to be constructed and displayed.
• Startup applications need to be launched.
Startup can be one of three experiences; boot, resume from sleep, or resume from hibernate. Although resume from sleep is the default, and often 2 to 5 seconds based on common hardware and standard software loads, this post is primarily about boot as that experience has been commented on frequently. For Windows 7, a top goal is to significantly increase the number of systems that experience very good boot times. In the lab, a very good system is one that boots in under 15 seconds.
You can read more over here.