rebuilding dis-assembled Dell Inspiron 620 for brother

[synario]

So I recently built a gaming PC and it's amazing~! I get 60 fps ultra settings any game I can throw at it.

However my brother is on an old laptop and I wanted to rebuild my dell desktop (inspiron 620) which would be more powerful than his laptop. I disassembled the dell, taking the hard drive and optical drive as well as my upgraded PSU for my new PC.

I've heard that you can't use an OEM version of windows 7 on a new motherboard. It will ONLY recognize the motherboard it came with.

However, what if I try to use a new version of windows 7 on my old dell motherboard? What will happen?

Could my brother put his macbook pro hard drive (which has a windows 7) partition into my old desktop and boot it up, even while using the OEM Dell motherboard/cpu?

EDIT: IF that wouldn't work, could we buy a new desktop hard drive, have my brother uninstall the windows partition off his laptop, and then reinstall his windows 7 copy onto the new hard drive using the OEM dell motherboard/parts?

 

[USAFRet]

1. 2 devices, you need 2 license keys. OEM, retail, whatever.

2. macbook hard drive in a whole different PC is unlikely to boot at all.

3. See #1

 

[synario]

Yep, so I do have a fresh copy of windows 7, no assigned devices.

With that, I can put it on an old dell motherboard, you are saying? If i use a fresh desktop hard drive?

The dell OEM motherboard won't reject it since its not the Dell OEM windows 7?

 

[USAFRet]

Yep, so I do have a fresh copy of windows 7, no assigned devices.

With that, I can put it on an old dell motherboard, you are saying? If i use a fresh desktop hard drive?

The dell OEM motherboard won't reject it since its not the Dell OEM windows 7?

If you an unused OS license key, sure. Install away. Old drive, new drive, whatever.

The system does not care what OS is on it.
An OEM license cares what system it was originally installed on.