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.