I recall reading that the Kensington cable type locks are basically useless, and can be easily opened with nothing more than a ball point pen top (as well as other things). I'm sure the technique is easily learned online. I wouldn't count on a cable lock to require a thief to cut the cable or damage the laptop, or even to slow a thief down much.

I currently have one of the small Dells (D410) which generally fits in a room safe; unfortunately it's replacement time, and I'm looking at having to move to a larger laptop as the newer smallish versions of the 410 available at my shop (D430) don't have such a good reputation, and the other option (a 630) is probably too large, and so this now is an issue for me too. But for me, the issue is much more one of securing data than the hardware, so my solution likely will be to swap in a hard disk that reliably and securely encrypts, and hope for the best (the company will pay for a new laptop). There's ton's of good info on encryption options buried in the (transcribed) Security Now podcasts at www.grc.com--I seem to recall that the writer (Steve Gibson) liked a fairly new Toshiba laptop hard disk for that purpose.