Can anyone offer tips about what to look for when buying computer speakers? Thanks.
You are basically looking for the same specs as regular speakers. Figure out if your sound card supports surround sound (more channels then stereo). If it does, then you can get higher end speakers, but you my not need it.
Brand makes a difference. If you want quality sound - generally you will want some sort of a name brand.
Wattage. The higher the wattage (>40) the better. It gives you more power, so when you play lower volume sounds it will put less stress on the physical parts.
Frequency response. Unfortunately I do not know enough about it, but I know it makes a difference, especially for desktop speakers that will play low sounds.
Good luck. Post what you find so you can get a product specific review.