Tom’s Hardware Guide has a good CPU performance guide for 2005 – 2006, where you can compare various processors and brands, if you are curious about stats.
You can access it at www23.tomshardware.com/cpu.html.
Note: This isn’t really geared towards mobile CPUs, but there are mobile versions of some of the CPUs available, as well as equivalent versions of the CPUs.
They unaccountably seem to omit all mobile chips, so it’s not much use for readers of this site…
The Sempron comparisons are interesting, as there is a mobile version (of course the harddrive and system bus are going to differ widely).