Install Vista as a time-limited trial

Begin by booting the PC from your Vista DVD. You’ll need to make sure that ‘Boot from CD’ is enabled in your PC’s BIOS Setup configuration, of course. Choose
‘Install now’ when prompted to begin the Vista installation, but be
sure to click ‘Next’ without entering the product key to install Vista
as a trail Evaluation installation.


Ensure you select the Vista version which matches the one you’ve purchased. Follow the prompts until you complete the installation and arrive at the Vista desktop. At
this stage you have a functioning Vista installation, which will allow
you to work until the 30-day evaluation period expires before entering
the ‘reduced function’ mode which only allows you to perform activation. Online activation isn’t yet possible, because you haven’t entered the product key yet.


Before
making changes which will allow you to activate the installation it is
best to do all the device driver installation, software installation
and testing which is needed to have Vista configured and operating the
way you want it to. Activate now and then later find that your Vista install has problems and you’d need to start over again. That’s why Microsoft always allows a ‘grace’ period before you need to activate. Get everything working correctly first!


The following simple tweaks will allow you to turn the trial installation into a valid and activated one. Once you have completed the process of getting everything installed, configured and tested continue on with these instructions.

Disable User Account Control

Begin by disabling User Account Control (UAC). There are numerous methods for doing this, but the quickest and simplest is a registry edit.

With UAC
disabled you can now issue a couple of commands which will fully
activate your Vista installation using the Product key which
accompanied your Vista Upgrade purchase.


Hold down the Windows key and tap ‘R’ to get the Run dialogue box.


To assign your product key to the installation issue the command:

cscript C:\windows\system32\slmgr.vbs -ipk <upgrade product key>

(Don’t type <upgrade product key> of course. That where your actual product key goes, in full!)


You can now activate your installation online by firing up the ‘Run dialogue again and issuing the command:

cscript C:\windows\system32\slmgr.vbs –ato


Verify that Vista is activated by issuing the command:

cscript c:\windows\system32\slmgr.vbs –dlv

There you go! A
fully functioning and activated Vista installation on your new hard
drive, using your Vista Upgrade purchase, without needing to install
Windows XP first! Re-enable User Account Control if you want to use
the feature.

You can re-use a hard drive using this method also. If
the drive you have isn’t a new one, and already has an existing Windows
installation on it, download the drive management utilities available
on your hard drive manufacturer’s website. Be sure to get the boot floppy or boot CD download. Boot
your PC from that first, use the available tools to ‘wipe’ the drive,
and then reboot from the Vista DVD to perform the Vista installation.

Credits go to techwrighter not me