With many different processors in the market (AMD, Intel) and versions in them (Celeron, i3, i5, i7, Phenom, Athlon, Turion) it has been increasingly difficult to compare prices and performance. I found the following sites extremely useful :-
PassMark Software has delved into the thousands of benchmark results that PerformanceTest users have posted to its web site and produced five Intel vs AMD CPU charts to help compare the relative speeds of the different processors. Included in this list are CPUs designed for servers and workstations (Intel Xeon and AMD Opteron processors), desktop CPUs (Intel Core2 Quad, Intel Core i7, Intel Core2 Extreme and AMD Phenom II processors), in addition to mobile CPUs.
Provides serious and competent information about laptops and notebooks. Notebookcheck provides tests, reviews, news, technical information (like CPU and GPU comparisons) and links to reviews by other sites.