Checking your system Install Date and time in windows vista, open command prompt or dos and use this command.
Follow these steps:
1.Press window logo +R
2.Type cmd in run window and enter.
3.Type Systeminfo in command prompt and enter.
4.Waiting for some time…and all report display.
5.Check this line in report -Original Install Date:6/17/2007, 4:59:40 PM (as your system)
If you want to save this report in text file-Type systeminfo>report.txt and enter, waiting for some time and then type report.txt and enter.
--