My set didn't have a headphone jack, a big downfall, but I think that recent editions do, so it shouldn't be a big deal.
They also are NOT equivalent to a home stereo, as some people on here claim. The sound quality at ear splitting volume levels is not nearly as good as a good home stereo, and the bass tends to get muddy at high continuous levels, BUT you don't normally turn your computer up that loud since you sit in front of it.
A few weeks ago, I got a new PC and it came with BA7800 (not on Amazon yet). These have 4 sat. spkrs and a huge 8 in. woofer. Amazing sound comes out of these, even using just the two front speakers and the woofer you get a better "full" sound and projection with these.
The verdict: great speakers for the price, but don't expect to DJ a party with them. Should be more than enough for not-too-picky audiophiles. Make sure your sound card supports the digital output if you have an older PC!!
Speaking as someone who bought his first stereo system with a school loan in the 70's I'm just amazed at the sound quality these speakers produce for well under $100. As for the volume and control complaints that a few people mentioned it is true that my son's electric guitar amp is louder. Of ocurse it's three feet tall. And there are very few controls on the speakers themselves which is just fine since every software program that plays music has an equalizer, balance control and such in it. I really don't need to set volume or balance six different ways.
I'm sure there are better speakers out there but with these you are well into the land of diminishing returns. By that I mean you'd need to spend a LOT to improve quality much at all. Get 'em, listen to 'em and see.