We also checked out the PODS company. PODS lets you keep the container longer, and it's at ground level, so you can fill it as you pack, but it's a little more expensive for the move. What's not clear on their website, is the cost per day as you're packing it.
UPack only gives you the container for two days, so you have to get everything packed and ready to go, but it's less expensive to move with them, than the PODS. Both sites have a way to estimate moving costs, though.
UPack is the one I'm planning on going with for my move.
I don't have that much, but it's enough to where I can't ship it all via USPS or UPS.
Good info on those companies. As I was helping my brother move this weekend (movers were out of the budget and his wife is expecting again so no lifting for her...) we decided that when it comes time to move mom out to the east coast we're going to use one of those container companies.... and hire someone to unpack it.