How do I move my wallet from Windows 7 to a new Windows 10 machine? Previous answers say set up a new wallet with new address and transfer bitcoins to new address, is this the only way of doing it? I don't want to wait days for the new wallet to download blockchain and verify when I already have that on the Windows 7 machine.
First - you didn't specify if you use Bitcoin Core or any other program for maintaining your wallet, so the answer below presumes you used Bitcoin Core.

The short version: it stores all of its data in %AppData%\Bitcoin
This folder usually translates to C:\users\\AppData\Bitcoin

Underneath that folder you will find there the 'wallet.dat' file.
This is the file that has all of your addresses (including private keys). This is the file you'll need to copy. 
You will find in that folder also a subfolder 'blocs' which is your local copy of the entire block chain.

On both Win7 and Win10 those files reside under the same folder - %AppData%\Bitcoin.

So - simple copy instructions:


Install Bitcoin on the new (win10) machine (and don't start it yet)
Stop Bitcoin on the old one
Copy %AppData%\Bitcoin\wallet.dat from old to the new one
You may also want to copy the entire %AppData%\Bitcoin\ folder with the rest of the files and block chain, or you can download it again (it's "only" 20+ gigabytes)
Once you're done with the copying you can start Bitcoin Core on the new computer.


That's all.

See https://en.bitcoin.it/wiki/Data_directory for more details.