The altec have a cleaner sound and can hit lower frequencys' the range is 20000/27, whereas the logitech have a frequency range of 20000/35. I have listened to both of them for I am also looking at getting either of those two or a 5.1. It depends on what is most important to you. The logitech have the best bass around, but its too much for me and not anough trebel-no way to adjust the treble level on the logitech. The altech seem to have a cleaner sound and as you can see a better range and you can adjust the treble. The nice thing about the logitechs is that they have a screw cap on back so you can use your own speaker wire for longer length-is that a great benefit? Pratically speaking -no, althought it is cool. Most people dont set there speakers that far back anyway or I should say that the standard speaker wire length on the altec is long enough anyway so it really shouldn't be a factor in picking your speakers. When the logitech came out there was nothing that could touch them for the money, thats why so many people in this froum bought them and would recommend them. If your a younge kid who is concerned most of all by a killer bass logitch is the answer. If you want more versitility in your sound control and are more concerned about sound quality I would go for the altech.
You can see the spec differences on price grabber.com