At least from what is posted on my notebooks dedicated forum, X1000forums.com (Compaq X1000 and HPZT3000 Pentium M Centrino 15.4" widescren -- equivalent to Dell 8600) the Dell case construction is not up to snuff (flexes) and the keyboards are often not as responsive as well.
If you look strictly at performance the Dell 8600 is a good choice as nearly no other notebook out there has the 128mb Dedicated video option (Compaq / HP above have up to 64mb) and it has the 7200 rpm Hitachi hard drive option (much faster than standard 4200rpm or even 5400rpm hard drives).
However, Dell has gotten a lot of complaints about the noise these hard drives make (sometimes clicking) if you don't activate the correct software so Dell has issued some sort of a software patch.
Dell's consumer computer service is in India but so is HP but this is a sore point (Apple is #1 in service and IBM is #2).
In general, the answer is that Dell has the components to make a good notebook in specification but their case construction, flex and keyboards do not match up in many cases.
This is similar to General Motors at least until recently. They have the engine horsepower and a good price but you know there is a difference inside the car (with the plastics and the creaks) versus a Honda or Toyota.
Also, the Dell 600M has a very warm spot to the left of the touchpad (hard drive is directly underneath it) and a woman complained about this after her return period expired. I went to a Dell Kiosk to try this a mall and it was quite warm in that area.
So, if you do consider a Dell, go to a kiosk in the mall and make sure you are satisfied with any heat issue, keyboard fell and especially pick up the notebook as many say they flex too much and in some cases crack.
The HPZT3000 and Compaq X1000 for example (similar to Dell 8600 but 6.5 pounds instead of Dell 8600 6.9 pounds) has an aluminum top and aluminum bezel surrounding the LCD so that makes it more rigid and the entire notebook (plastic casing on the bottom) doesn't flex when picked up. See www.X1000forums.com if you are interested in these and also read the comparison to the Dell 8600 in the general section of the forum.
You can also read Dell posts at www.notebookforums.com
Cnet is mostly focused on performance but you have to check out yourself the intangibles (case integrity, body flex, keyboard) as they are very important in a notebook and not very important on a desktop (which is not moved around or typed on directly).