This fall I got a new home machine, just a bit over exactly five years after I got my previous home machine. It happens that I saved the invoice for my five year old machine, so I dug it out today in order to do a comparison about what five years of progress in PC technology did and didn't change for me.

First off, the progress of five years got me much better prices. My recent home machine cost me only about 60% of what my old home machine did. By itself, this is pretty impressive. Apart from that, running down the major components:

• CPU: AMD dual core versus much faster Intel quad core. The Intel CPU was cheaper but not by a substantial amount; I think the AMD was probably closer to the high end at the time. I don't know what the benchmark results are, but I got a substantial performance improvement.

• RAM: This is perhaps the most striking change on a purely numerical level; in 2006 I got 2GB of RAM for more than twice as much as what 16 GB of RAM cost me in 2011. Even in 2006, 2 GB was clearly economizing (I remember debating with myself over 2 GB versus the extra money for 4 GB and deciding that 2 GB should be good enough). In 2011, 16 GB is as much as the motherboard will take with current DIMM densities.

  In short, desktop RAM has become stupid cheap.

  (One index of the change is that in 2006, the 2 GB of RAM cost more than the CPU and was the most expensive single component. In 2011, the 16 GB cost only a bit over half of the CPU.)

• motherboard: the modern era features more SATA, less IDE, more USB, and not even one external serial port. Motherboards are unexciting. Even in 2006 the motherboard had onboard sound and gigabit Ethernet. The 2011 motherboard probably has better onboard sound, but in practice this doesn't matter to me; my sound needs are modest.

  (The 2006 motherboard was a bit cheaper than the 2011 motherboard, but neither were particularly expensive or advanced ones.)

• Hard drives changed only moderately at one level; in 2006 I got 320 GB drives for somewhat over twice what 2011's 500 GB drives cost me. In 2011, 500 GB drives are nowhere near state of the art; in 2006, 320 GB drives were not that far out of it.

  (This was before the floods in Thailand.)

  On another level, they changed a lot. The 320 GB hard drives of 2006 were my only storage. The 500 GB drives of 2011 are only for the operating system; my data lives on a pair of 1.5 TB drives (that I had upgraded to some time ago). 500 GB is way overkill for the OS, but there's no real point in using drives that are any smaller; it's not like I'd have saved any significant amount of money.

• Video card: ATI X800 GT versus ATI HD 5450 with double the memory for less than a third of the price. Toms Hardware theoretically puts these two cards in almost the same performance category, although I'm not sure that's really true. In practice, what happened between 2006 and 2011 is that graphics cards shifted to the point where a basic passively cooled card was clearly more than good enough for what I was doing, even for driving dual displays digitally.

  (I don't yet have dual displays at home, but I do at work and my work machine uses the same card. In fact, my work machine is now a clone of my home machine, just as it was in 2006.)

• optical drives: in 2006 a DVD burner cost about four times what it did in 2011, and I thought I would listen to CDs enough to justify having a separate CD/DVD reader (rather than put wear and tear on an expensive burner).

  (I was wrong; my CD listening had already dropped off a cliff in early 2006 and never recovered. I still kind of miss that sometimes.)

• Power supply: in 2006 I didn't trust the power supply that came with the case to really be a good solid one that delivered enough power so I bought a separate one as well. In 2011 I couldn't find any reason to worry about it so I didn't; the power supply you get with a decent quiet case these days is going to be quite good, more than you need (for a PC like the kind I build), and efficient.

In 2006, the most expensive components were the RAM, the CPU, the two hard drives together, and then the video card. In 2011, the most expensive components were the CPU, the motherboard, and the case (more or less tying with the RAM). Another way to put it is that in 2011, the video card, the DVD burner, the hard drives, and pretty much the RAM were all what I considered trivial expenses in the overall machine.