If you bought that Lenovo brand new, it most likely was a clean install. Upgrades aren't all that obvious sometimes though but issues with them often manifest themselves in very strange ways. But again, if it was new or even refurbished, I seriously doubt it was an upgrade. If you bought it used however, tough to say. Haven't done too many upgrades but from what I've seen, I believe there are folders left over with odd names such as "INPLACE" and some others akin to that.