can I upgrade from Windows 7 to Windows 10 w/ Core Duo 2/40GHz E4600 64 bit and 4GB?

[AlHill]

Well, yes. Be aware Windows 10 does not support this 2007 processor, but it will run.

https://ark.intel.com/content/www/us/en/ark/products/32242/intel-core-2-duo-processor-e4600-2m-cache-2-40-ghz-800-mhz-fsb.html

Also, I do not know your graphics. Are you using onboard graphics, or an add-on card (nvidia, amd)? Whatever the case, at a minimum, Microsoft will have a driver for it, although not necessarily the best.

Your 4GB memory is a minimum, but should be ok.

How much disk do you have?

You can upgrade to Windows 10 Home, and activate with your Windows 7 Key.

Now, remember that your computer is twelve years old. Components may begin to breakdown and fail. You may want to consider upgrading to a new(er) machine that is supported on Windows 10.

Doc

[AlHill]

Also, go here to upgrade: https://www.microsoft.com/en-us/software-download/windows10

Doc

[JRobb7]

Technically, yes, but it's going to be dog slow. I won't bother putting Windows 10 on anything less than a 3rd gen i5 with at least 8GB of memory.