Take a look at the below website. I wouldn't say the ratings on central processing units on this website are exact, but it gives you a general idea on performance.
Edit: Might I also add, almost all desktops really beat laptops in processing power and in the category of future upgrades. Unless portability is a really big issue go with a desktop computer.
Just one general obsevation from me on cpubenchmark.net, I don't know how they do the ratings on some of the processors.
The Phenom 9950 Quad-Core is rated at a 2,950 while they rate the Phenom II 805 Quad-Core Processor at a 2,887. The Phenom II 805 has twice the Level 3 Cache of the Phenom 9950. In addition the 45 nanometer technology of the Phenom II 805 would really beat the 65 nanometer technology of the Phenom 9950. The Phenom II 805 should be rated higher than they have it rated on cpubenchmark.net.
The Phenom II 805 Processor would not completely crush the Phenom 9950 in processing power. From what I have heard the Phenom II generation of processors beat the Phenom first generation clock for clock by about 30 percent.