Computer chips are made in "A Clean, Well-Lighted Place." Kudos to a 1926 short story by Ernest Hemingway. I don't think Hemingway anticipated today's computer clean rooms and complex nanometer manufacturing technology. After all in 1926 computer chips didn't even exist. We've come a long way since then.
Two companies dominate the computer chip market, the market leader, Intel, and the "Avis" of computer chips, AMD. Not that there aren't other manufacturers, it's just that your x86 desktop architecture is dominated by these two companies. Intel created the x86 architecture back in 1978 and it is the architecture, by making sure we can always run legacy code, that persists to this day. You would think that this would make it easy to make a choice. But...if you go to the Intel web site and look at all their processors, you'll be at a loss to pick the right computer chip for the system your building. AMD, which also supports the X86 architecture, has less choices, but there's enough processors to still make it difficult to know which one to choose.
We could go through a bunch of specs, comparing this against that, but you would still be overwhelmed by the choices. We are going to approach this slightly differently. Since the computer chip is mounted on a motherboard, computer chips and motherboards are intimately connected. It does you no good to pick out a super fast chip, and not find any motherboards that can run the chip.
Computer chips are mounted in sockets on the motherboard. In order to increase your overall system options, we want to pick the cpu socket that has the most motherboards available. For Intel the current socket of choice is called "LGA 775." LGA stands for "Land Grid Array" and the socket has no holes, instead it has posts that mate with pins on the bottom of the chip. The current popular chip that uses that socket is the Intel Core 2 Duo. Yes, there are faster Intel chips, like the i7 with 45nm techology that takes a "LGA 1366" socket, and other Intel chip types, like Quad core, but at this point in time in software development, the Core 2 Duo is more than adequate. You can tell one Core 2 Duo chip from another by their "E" number. The higher the number, the faster the chip, and the higher the price. E numbers E6850 and below are 65 nanometer technology and E7200 and above are 45nm technology. The 45nm are denser and faster. That's about all you need to know. I admit this is simplistic, but you can't go too wrong with this approach. The chip you pick will be the highest E number Core 2 Duo that fits in with your overall budget.
Let's take a peak at the AMD chip set. There are actually two sockets we could choose with AMD. The AM2+/AM2, or AM3. Theoretically the AM3 will work in an AM2+ socket, while an AM2+ chipset will not work in an AM3 socket. To be safe, if the chipsets calls for an AM3 socket use an AM3 socket motherboard only. This corresponds to the Athlon X2 chipset for the AM2+, and Athlon II and Phenom II processors for the AM3 socket. The chief difference is the Athlon X2 chip set uses 65 nanometer technology and the Athlon II and Phenom II uses 45 nanometer technology. Just like with Intel the higher the number of the chip the faster the performance. Both the AMD chips are Intel chips are fairly equivalent. See my previous blog entitled, "Quad Core Battleground coming in 2009," for some more details.
I favor the Intel chips sets at present, but I have to admit I don't have experience running an AMD chip set. I don't see any problems in using AMD, as long as the motherboard has the correct AMD socket.
Now which chip to purchase? This is dependent on how much money you want to spend on your overall system. You could buy an expensive chip, bear in mind, that you will probably then want to buy an expensive motherboard, and an expensive graphic card. The next thing you know, you may be way outside your budget unless you are planning on building one of those dream computer gaming rigs. If your outside your budget you can move to the next lower E number chipset or lower number AMD chipset. I think you'll find unless your building the hottest system you can imagine, a processor running above 2.6 Ghz is probably adequate at this point in time for a home computer. If your going to run a Microsoft Windows7 you'll probably want a fairly fast chip as all those 3d graphics on the desktop come at a performance price.