At the present time you have 3 choices for affordable (keyword there) multi-core processors, that being dual-core, triple-core and quad-core.

If you're going Intel you can do duals and quads. With AMD you have duals, triples and quads.

No matter what brand you go with, multi-core (sometimes known as many-core) is the way to go. They run circles around single-core CPUs, and if you're not running one, you should, plain and simple.

As of now multi-core is cheap to run, and the motherboards that support them are also cheap to own and run.

On the Intel side, a retail-boxed (meaning it includes the fan and all that stuff) dual-core non-Celeron is $69.

On the AMD side, a retail-boxed dual-core is $45. True to tradition, when going AMD you do save money over Intel - both on the CPU and the motherboard.

And by the way, that AMD I linked is only a 45-watt. It's cool, as in literally cool-running compared to the Intel which is a 65-watt.

The choice of which company to go with is ultimately your decision. At the present time I'm running an Intel dual-core and yeah, it's awesome. But I'm quite sure AMD duals are just as nice.

For those of you out there wondering whether Windows XP has any issues with multi-core, the answer is no. XP has absolutely no issues with a multi-core processor. In fact, when I first used a multi-core with XP I was surprised it didn't have any issues whatsoever. It just booted and ran exactly like it was supposed to do the first time and every time after that.

Multi-core is not expensive, and said honestly it's the best possible upgrade you could do. Once you go multi, you never, repeat, never go back. :-)

Let me say it another way. Have you ever dabbled in overclocking or the like with single-core CPUs? You don't even need to bother when running multi-core. They're plenty fast enough right out of the box. Yes, some super-gamer types may argue to the contrary, but for the rest of us, multi-core as-is is more than enough.