@umbra21 - You don't just want to keep boxes in order to be able to send them into the shop. I'm moving overseas in a few months and I'm really glad I saved all of the boxes for my desktop because it would be impossible to pack if I hadn't.
I'm not going to bring the whole thing, of course, just the more expensive parts of it like the hard drive and the graphics card. But you have to have anti-static bags to transport that kind of stuff and it's so much easier to just keep the ones it came with than to try and find more.
Decent moving boxes in general are annoying to find, so I'm glad I've had so many stored away in the garage. They just need a bit of packing tape and they will be ready to go.