32bit to 64bit system advice.

My old PC died and I bought a secondhand one but without me realising it was a 32bit Windows 7 Ultimate, so I couldn't install Orbx on my FSX and my X-plane11 as they require a 64bit system.

Anyway I think I got round it by buying a 1tg hard drive with Windoows 10 64bit pre-installed, is there anything I should look out for when fitting the new drive in the PC, obviously I will remove or disconnect the old one, could I uninstall Windows 7 from it and will it still be recognised by the PC?

Reason I ask is I was hoping to copy a lot of files over.

Col.