Team Fortress 2 Server Up!!!

[Lkr]

lol, pilot, your old rig to the one you built at the beginning of last year isn't an upgrade. its a whole new machine.

[Pilot_51]

It depends entirely on how you look at it. You don't build or repair PC's anything like I do so I don't agree with your PC terminology in this case.
Most of the hardware in my main PC before the upgrade is still in my main PC after the upgrade, so by far I still call it a major upgrade ("major" because of the components upgraded) rather than a new PC.
If I only want to upgrade the case, I essentially need to take the PC completely apart (except for removing the CPU/heatsink/fan from the motherboard) and put it back together in the new case. Is that a completely new PC? No. It'll probably look completely new, but it's the same old system.
If I upgrade the case and the PSU and a couple drives and the keyboard and the motherboard and everything else that I need to upgrade with the motherboard, then I'll probably call it a new PC rather than an upgrade since I'll pretty much have an extra PC to build with the old parts.