No, it wouldn't be 'like' a brand new computer, for all intents and purposes it would 'be' a new computer. There is no upgrade. You'd need a new motherboard, new ram, new cpu, (you'd get a new gpu anyway), so the only things reused would be the case and storage. Yep, new pc.
As far as harm, the only harm done would come with the new motherboard, it would invalidate your copy of Windows. To fix that, you contact Microsoft directly by phone, and tech support will checkout the pc and hopefully issue a new key (they'll register it remotely). Do this before clean install of windows, which will be needed as you'll need to wipe out the amd mobo drivers and install the Intel mobo drivers and they'll conflict if you don't.