The choice of hardware depends obviously on what the system is going to be for. So I start with a list of things I want to be able to do with it:
And one more thing it has to be able to do:
So, given that last requirement, we're looking at a laptop. So that means paying more than for a desktop of equal capability, but it does mean I can also use it on the train etc. If I want to carry it around I don't want more than a 15-inch screen, but in order to type it's got to be bigger than 12. Screen resolution is a big one, in order to work in several windows it really needs more than 1024x768 resolution, which seems to be standard. Widescreens don't help when you're vertically scrolling documents, so the WXGA ones aren't of much interest. None of those requirements are very demanding on the processor, so a top-speed processor is not on the priority list. It would actually be nice to have a slower processor, so that the battery lasts longer, the chips generate less heat and the fans don't have to work so hard or so noisy to keep the thing cool. For the peripherals it needs at least USB, and firewire would be nice for future video transfers. A serial port would also be good for the GPS, as although you can get serial-to-USB connectors, it's another thing that might be tricky to get working. The hard disk should be fast but not necessarily massive. A DVD-player is more or less standard for a new box, as is a CD-writer (useful for backing-up) - I don't need a DVD-writer yet but those video files will undoubtedly only get bigger...
So the requirements sheet now looks like this: