I shipped my computer cross-country with UPS. It just arrived in San Jose (where I am staying for the summer), and it is completely trashed. When I opened the box, both the sound and video cards were popped out of their slots, and the metal guards for them on the back of the case were bent. A few chips on the motherboard itself were knocked off, apparently by one of the 5.25" bay covers which was also knocked out... the best description would be one my friend made soon after I opened the box: "Damn, that box looks like it went through a f**** meat grinder".
I am not happy with UPS...