I just buy whatever is cheapest that has enough CPU and memory, and ideally as large a screen as possible.
Pretty much this, though I do do some checking around to make sure it's not a cheap piece of crap before I buy. Getting it refurbished instead of new helps, too, as long as it's the kind of refurbisher that offers warranties.
Currently I've got a Compaq nc4400 - 12" 1024x768 screen (I wanted to move up from my Eee's 9" screen, but I hate the widescreen gigalaptops that seem to be ubiquitous these days,) Core 2 Duo @ 1.83GHz, 2GB RAM (I intend to kick this up to 4GB in the near future, that should let me turn off the pagefile altogether.) The resolution isn't exactly impressive and it's another friggin' Intel 950 video chip, but I don't need much acceleration, and I
greatly prefer 4:3 screens. It's got a decent array of ports, even a PCMCIA slot, but annoyingly the three USB ports are placed one to each side (front excepted.) I've heard a lot of unkind words for modern HP products, but this seems to be fairly solid, though I've never had a computer where the plastic felt so much like Rubbermaid.
But in any event, it was cheap, fits my performance needs, and meets my most important criteria:
it runs Windows XP. The pre-purchase research for every model I looked at involved checking the manufacturer's website for XP drivers :lol:
Also got a Haiku partition on there, which I've been experimenting with. It's got a ways to go yet (for one, they need to fix power-management support on multicore systems - at present it damn near boils and it's only the mighty fan and the fact that I replaced the thermal paste with high-quality stuff when I bought it that keeps it from overheating proper,) but it's very intriguing, and I look forward to seeing what it's like when they get the bugs worked out
