I don't have experience with the Inspiron 600m or 6000, but none of the people I know who own Dell notebooks has had any problems with them.
Because of performance issues, I wouldn't recommend the 600m. The 6000 is quite heavy, so beware.
Do you require a Dell, or would you like to save some cash and go with a cheaper and faster non-Dell notebook?
I'm looking for a notebook for school, I'm considering the Dell Inspiron 600m or the Inspiron 6000. My main concern is that I've heard horror stories about Dell notebooks having massive hardware problems. Does anyone have any experience with either of these regarding their reliabiliity?