It's probably a bigger pain to make sure windows works with your new components than it is to reinstall it, though it might "just work". I've always done a clean install after a major hardware change like the motherboard. It's usually pretty easy to move your Windows license over by calling them... But I've never tried it with an OEM license, so I don't know about that.
Although I've found that if you may have to buy a new copy. They tend to have use limits of about 5 PCs, regardless of whether its an upgrade or not. I'm no PC expert, but that's been my experience with the use of Windows 7. You'll most likely have to reinstall it. Any important components, apart from certain ones, will usually result in you having to reinstall a lot of stuff.
You don't actually have to buy a new license, you just have to go through the trouble of calling Microsoft to activate it on a new computer.
Edited by AAAAAA: 1/11/2013 6:40:56 PMMS will not change your licence for you. It's in the FAQ. http://www.microsoft.com/oem/en/licensing/sblicensing/pages/licensing_faq.aspx#fbid=S5hSwZqGaRJ [quote]A. Generally, an end user can upgrade or replace all of the hardware components on a computer—except the motherboard—and still retain the license for the original Microsoft OEM operating system software. If the motherboard is upgraded or replaced for reasons other than a defect, then a new computer has been created. Microsoft OEM operating system software cannot be transferred to the new computer, and the license of new operating system software is required. If the motherboard is replaced because it is defective, you do not need to acquire a new operating system license for the PC as long as the replacement motherboard is the same make/model or the same manufacturer's replacement/equivalent, as defined by the manufacturer's warranty. The reason for this licensing rule primarily relates to the End User Software License Terms and the support of the software covered by those terms. The End User Software License Terms are a set of usage rights granted to the end user by the PC manufacturer, and relate only to rights for that software as installed on that particular PC. The system builder is required to support the software on the original PC. Understanding that end users, over time, upgrade their PCs with different components, Microsoft needed to have one base component "left standing" that would still define the original PC. Since the motherboard contains the CPU and is the "heart and soul" of the PC, when the motherboard is replaced (for reasons other than defect) a new PC is essentially created. The original system builder did not manufacture this new PC, and therefore cannot be expected to support it. [/quote]
"The motherboard exploded or something!" I've never actually talked to anything except a machine when I call Microsoft about licenses, so I guess that wouldn't work. Oh well. Guess he'll have to get a new license.