I have a D630 and I agree; it is a laptop and does all the right laptop things. However: I got my wife a Dell E4300 and had many problems. Other colleagues have got other E series Dells have have had basic problems like not being able to suspend/resume under Windows and being forced to run a single core to get basic reliable operation.
See, for example:
http://en.community.dell.com/forums/t/19245498.aspx?PageInde...
http://www.datapoohbah.com/tech/2008/12/16/dell-e4300-is-bit...
I don't know if things have improved, but based on my experience the D630 was the last good laptop from Dell.