For the record, I got in a few E6500s and their build quality is excellent. We also recently got in some Lenovo Thinkpad T61s and I'd say that the Dells have significantly less body flex, not that the Lenovos are flimsy.

The latch mechanism on the Lenovo is better: less awkward to operate, dual catches. Also, I prefer the way the Lenovo's lid/screen wraps around the body a little bit when closed. The Dell just sandwiches together. Also, the Lenovo has squarer, flatter sides. The nose of the Dell has seven different angles, which means that it's always going to have its weight on an edge when you have it sitting vertically in a bag. And it seems like it's going to be far easier to ding one of those edges.

The Dell website seems to have lied about the weight of the laptop. It claims 5.2lbs. Mine weighs 5.6lbs. with no battery. With the battery (9-cell), it weighs 6.7 lbs. I was definitely hoping for a lighter weight. The Lenovo actually weighs less, despite the fact that the specs say it should weigh more. So I'm disappointed about that.

The laptops both have all of these ports: USB, VGA, PCCard, ExpressCard, Ethernet, 4-pin FireWire, headphone, microphone. The Lenovo has the following ports in addition: multi-format flash card reader, modem. The Dell has these in addition: SD card reader, smartcard reader, DisplayPort, eSATA. Also, the Lenovo has the PCCard and ExpressCard ports contiguous, probably so you can use an old Type-III PCMCIA card. The Lenovo has 3 USB ports, while the Dell has four, one of which is also the eSATA port.

The docking stations have their own pluses and minuses. The big plus for the Dell is dual DVI ports. The big plus for the Lenovo is better construction and more soft-buttons, by which I mean buttons that send signals to eject, rather than just doing a hard eject of the laptop. I've yet to comparison test the docking stations more in depth.

Honestly, I'm not super-happy with either of them. They're both too big, but they're the smallest I can find that meet my requirement of having a screen equal to or greater than 1400x1050 in both dimensions. I have other requirements, too, but that was the most restrictive one.