I’ve just finished writing my column for the latest issue of Custom PC, and was focussing on how many e-mails we get from readers who want to know when the best time to buy a graphics card is. It depends on how you look at it, I wrote: if you want the most speed for your money, then frankly, tomorrow will always bring a faster, cheaper card.

Having seen a lot of technology come and go, I think the best way to know when to buy tech is to consider what you want it do: or at least, to balance this consideration with objective benchmarks and tech-specs. After all, if you buy a graphics card to play Oblivion or Command & Conquer 3 on your 20in widescreen TFT, and you do research and it can do this, does it really matter if a slightly faster one appears next month? If you’re buying something just because it’s the latest-n-greatest, then of course you’ll be disappointed when it becomes obsolete.

Turns out I get to eat a nice dose of my own medicine, because today Nikon’s announced a new dSLR, the D40x, boosting it from 6 to 10 megapixels. Does it, as Engadget snidely says, make the D40 seem totally out of date? Not for me: I only got my D40 a month or so ago, but it’s a great camera, and it’s been great for what I wanted it for: a light, small budget beginner’s dSLR with a great kit lens. It was that yesterday, and it’ll be that tomorrow.

Buy tech to do something, not be something.