Win 7 Home to Pro

Background:
I have a Windows 7 Home Premium 64-bit PC which has been built for several months now and I'm very happy with it. I have configured it so Windows is installed and boots from a small SSD drive. I have a large HDD which contains the profiles, Program files, user data etc.

I am now wanting to complete the MCTS coursework from a Sybex book (Exam 70-680) and need a PC to carry out exercises on. My Win 7 Home based OS is not suitable for many of the exercises, I really need Pro. I don't particularly want to pay the £120 UKP to upgrade the O/S to Pro, neither do I want to chance of messing the install up when carrying out the exercises.

So I have been thinking about about buying another HDD and a copy of Win7 Pro OEM, temporarily taking out my existing drives and running the Pro for a few weeks/months. With a view to putting the system back to the configuartion its in now, some time in the future.

Question:
Will the Microsoft Activation system be happy with two O/S's using the same hardware? How does Activation identify the hardware in the machine to the license number?

In addition to what Kegger says, you don't need to keep the other HD's unplugged after installing Pro on its HD.

In fact the best method to multi-boot Win7 cleanly is to use the BIOS: after install plug back in the other HD's and set the preferred HD to boot first in BIOS setup, then use the one-time BIOS boot menu key to boot the other OS.

If you find this clumsy or don't have a BBS key then you can install EasyBCD (earlier versions are still free) to either OS to add the other one to a Dual Boot. Each will still keep its boot files so they can come and go as you please, whereas if you'd leave the extant Win7 HD plugged in during Pro install the installer would only update the boot files on Home Premium to boot Pro, requiring them to be recovered later into Pro for it to boot on its own.

Thank you all for your help, thanks particularly to Gregrocker for providing such a detailed answer:).
I will disconnect the existing drives whilst installing 7 Pro.

Hello, this is my first post on this site but I'm excited about being a part of this community.

I am also studying for this exam and am having fun expanding my knowledge base of Windows 7. That being said, I just wanted to suggest that maybe you download the free Windows 7 Enterprise Trial (90 days) from...

http://technet.microsoft.com/en-us/evalcenter/cc442495

From the books and sites I've been studying, I am finding that some objectives covered on the exam are only available in the Ultimate or Enterprise versions. (Such as booting from a VHD...) This might save you some cash and since you are only looking for an OS for a few weeks or months, this might save you some time down the road.

Hope that helps.

Welcome to SevenForums, pamccabe.

That's a very good idea! Check it out, kranky.