Windows 7 was available in general release October 2009.
Mainstream support for Windows 7 ends January 2015; extended support ends January 2020.
PowerShell v2 was included in Windows 7. You can download and update to PowerShell v3 or v4
# PowerShell script to output days of support remaining for Windows 7
New-TimeSpan -Start (get-date) -End 01/07/2020
Sales of the consumer version of Windows 7 Home ended in October 2014. This means OEMs can no longer offer it as an option on their systems. Windows 7 Pro is still available pre-installed.
Loading Windows 7 from scratch? Windows Update will hit a bug due to the large number of updates (including superceded updates) it must process, and slow to a crawl, taking hours and in some cases days to complete. See this thread on SuperUser for discussion. Or have a look at our solution, which should complete all updates in less than 2 hours.
Windows Vista was available in in general release January, 2007.
Mainstream support for Vista ended April 2012. It will be in extended support until April 2017.
PowerShell v1 was first introduced and included with Vista. You can download and update to PowerShell v3
# PowerShell script to output days of support remaining for Vista
$EoLVista = [DateTime]'2017-04-10'
$EoLVista - $(get-date)
Issues with Windows Update
Boot Configuration Data in Windows Vista - downloadable paper explains BCD in detail. Applies to Win7, too.
If command line isn't your thing, you can use this Microsoft tool.
Lifecycle Support Policy Definitions