Which Processor For My Needs?

Nearly any laptop processor made in the last three years will meet or exceed the performance of a P4 2.2 except, possibly, a slower Celeron. There are other reasons to avoid Celerons, also -- they get poor battery life and build up lots of heat, for one.

The two competitors now are the Pentium M and Turion 64, both of which are excellent processors. The Turion 64 is faster in some respects and is less expensive, but is harder to find.

A word on clockspeeds: Laptop processors (and, basically, all processors other than the Pentium 4) run at lower clock speeds than Pentium 4's. This doesn't mean that they have lower performance; it means that they are simply more efficient and do more work per clock cycle (and, incidentally, do much, much more work per watt of power used).

For instance, my laptop has an Athlon 64 processor running at 2.2 GHz. However, its performance is roughly on par with a Pentium 4 running at 3.6 GHz. A rule of thumb is that one can take the clockspeed of a Pentium M, Athlon 64, or Turion 64 and multiply by 1.7 to get the clockspeed of an equally-performing Pentium 4.

If you don't want to see a performance drop, the most important thing isn't the processor: very few things these days are limited by the processor. Instead, make sure you get a fast hard drive: 5400 or 7200 RPM. Hard drive speed is the main area where laptops have a tendency to lag behind desktops in performance.

For companies, I recommend Asus out of the ones you listed. I've heard mixed reviews of some other brands (except IBM -- their problem is the price), but Asus machines get pretty much all positive reviews and are competitively priced as well. Check out the z71a (the z71v without the gaming graphics board) -- you can get one of the nicest machines on the market (in terms of features, screen quality, battery life, etc.) for $1100-1200.