Home Premiuim upgrade to Windows ultimate

I have Home Premiuim at present . I want to upgrade it to Ultimate .
Do i need to purchase the Windows Ultimate . Are there any links where I can download it for free .
Please also suggest from where should i purchase the Ultimate if I have to .

Also , Could anybody please direct me how do I go about the upgrade without formatting my computer . Is that possible ?
If Anytime Upgrade wizard is to be used how should i use it .

Any help on this is highly appreciated . Many thanks in advance .

Windows Anytime Upgrade - How to

I would go by the features needed. If you don't need the extra features in Ultimate then I would not spend the extra money.

Feature Comparison here: Compare Windows - Microsoft Windows

If you decide to go for Ultimate, use Anytime Upgrade as suggested as it costs less and is only takes 15 minutes to unlock the extra features while keeping everything else in place.

You can also use a retail Win7 upgrade or full version key in Anytime Upgrade.

Thnaks for the reply greg !.
Actually I want to install sharepoint 2010 on my system . And for that I would need to install a Hyper V and then Windows Server 2008 which would get installed on Windows 7 Home Premium .

Also IIS is not enabled in Home Premiuim .

Would I be able to do all that if I use Anytime Upgrade ?
Also could you please tell where would I get the full version key for that ?

Thanks in advance !!

@ignatzatsonic: Thanks for the link . I went through the tutorial .
Where would i find the upgrade key ? I know that sounds a very basic question but please excuse my ignorance :)

ignatzatsonic said:

Windows Anytime Upgrade - How to

Thnaks for the link Ig ! But where would I find the Upgrade key ? Please bear with my ignorance :).

You would buy it.

Windows Anytime Upgrade: frequently asked questions