I have an X60s (not the tablet edition). Bad *** little machine. GREAT battery life (7-8 hours on extended battery). I'm dual-booting vista and XP and have happy with it for over a year now.
Don't have the X60, but I have been very happy with my Lenovo ThinkPad Z61. From my experience the build quality of the Lenovo version of the ThinkPad is still very good.
tropheus, I have a tablet at work, but I use it as a laptop -- really as a desktop bc I have it docked to a fullsized monitor and have a fullsized wireless keyboard and wireless mouse. If you really use your laptop as a portable device and are adept with the stylus on your PDA you will love the tablet feature.
I have a ThinkPad T60P and had a T43 before that. Pretty durable machine and I have been very happy with them.
tropheus, I have no idea why you are looking at a tablet, but from my experience, after using one for about three months, the novelty wore off for me and I was wanting to go back to a notebook. So unless you have a specific need for a tablet, I'd advise against it. Furthermore, I'd recommend a convertible over the tablet such as the Panasonic CF-19. Given all that, if your choice is between a Lenovo Thinkpad and a HP, I'd go with the Lenovo.
When we are issued laptops at work we are given the choice of a notebook or tablet. Several people I know chose tablets for the lighter weight and are happy with that. Only drawback is tablets have no dvd built in and you have to get the external drive and cable kit and carry it around. Our company stuff is imaged so we aren't supposed to load any software anyway so it's no big deal except some people would like to watch movies when they travel. Both Lenovo and HP have light weight laptops with built in dvd drives, X61 and 2510p, which in my opinion would be ideal.
I decided against the tablets, but the primary interest was to be able to better track my hand written notes. I am abysmal at keeping files. I also decided against the business class laptops and went with an entertainment laptop from hp. AMD turion X2, 3 GB RAM (667 mhz), 17.1 HD monitor, 250 GB HD (5400), vista ultimate upgrade, DVD-RW, and the usual 4 usb ports, firewire, LAN, wireless, etc. Got it for right at $1000. A "business" laptop from hp with 1 GB RAM (667 mhz), 100 GB HD (5400), Intel centrino X2, similar peripherals but better wireless with a/b/g and n capabilities, 14 inch (non-HD) screen, DVD-ROM (not a burner), was about $1700 (hp 2510p). Don't ever say you need a "business" computer. sheez.