Laptop: Lenovo (IBM) T60p dual booting XP Professional and Ubuntu 8.10 at home (I generally use Ubuntu with VirtualBox running seamless Vista for when I need Excel to do finance things.)
Desktop: HP Pavilion Elite m9400t dual booting Ubuntu 8.10 and XP Professional runs most of the media functions at home and has two 1 TB externals that I store everything off of (sudo server)
at work we have almost all IBM's running XP Professional (laptops and desktops)
My girlfriend has a newer 17" (I think?) Macbook Pro... thing is HOT (temperature wise)- we took it to the Apple store in NYC and they basically said "yeah, we know...it's a design thing...we stopped calling them 'laptops' because we're afraid we'll get sued if one really overheats and burns someone"
That being said, it's a pretty nice computer but I just love the functionality and abuse resistance of my ThinkPad. I'll go so far as to say IBM makes the best business laptops (and I've owned laptops from just about every brand, including Apple) and the trackpoint etc make it invaluable. My work just issued me a new Lenovo R61 and it's nice, but I like the T series much better.
EDIT TO ADD: One other thing: Microsoft Office (Specifically Excel, Access, and Powerpoint) are bar non, the best software apps in their class... I have tried just about every other paid app and open source app (OpenOffice, etc) and NOTHING comes anywhere near the power of the Office suite...that's probably one of the reasons it makes up a huge percentage of Microsoft's sales per annum