I've got three laptops, a desktop, a Mac Mini, and a few servers. My main laptop is my 15" first-gen MacBook Pro, which is extremely long in tooth and will be replaced immediately at this next refresh. I use it mainly as a desktop replacement that I can take with me if need be; it is generally at a desk with a nice set of speakers and a couple of external hard drives attached.
My second laptop is a 9" Dell Mini 9 with an extended 14 hour battery running Win 7 and Snow Leopard. This computer is light, has no moving parts (SSD, no optical drive, no fans) and can actually last all day. It's not powerful, but for light note-taking, Internet browsing, or command-line programming it certainly gets the job done. I would love to upgrade this machine to an 11" MacBook Air, but that will have to wait for a while.
My third laptop is a crappy Dell 15.6" computer running Win 7. It's my work-provided laptop and is good for running Windows-only applications or for doing program testing under Windows, but that's about it. It has a very crappy 1366x768 resolution 16:9 glossy panel, which is not fun at all to work on. I didn't pay for it and I don't own it, though, so I can't really complain all that much about it.
My desktop is an ancient Pentium 4B, 3.06ghz machine (something like 10 years old now, it was the very first chip with enabled hyperthreading) which is running Ubuntu. I mostly use this machine as a file server or for the occasional old computer game (under XP Pro). If I didn't have around 4 TB worth of hard drives and files in this thing (from back when a 120 GB drive was considered massive!), I probably would have retired it a while ago. I do wish to eventually have a modern desktop computer, but upgrading my ancient MBP is my priority at this time.