The X-540 is an exceptional PC speaker system.
Dooh, I just made myself look like a total idiot. The X-540 is a 5-channel system, while the Altec FX4021 is only a 2-channel system. Oh well, I suppose in this price range it's better to go 2.1 and get the better speakers than to try and pull off 5.1 sound.
No, the product lacks support for surround sound on several devices listed on the box making your comparison correct in those cases. The box list PC, CD, MP3, DVD, Playstation 3, and Xbox.
Most gaming desktop PCs have three audio outputs, required to get surround sound out of the X-540, making this a PC speaker system. For a desktop PC and a small space this is an exceptionally priced system that looks great.
When does the X-540 compare to the Altec FX4021? For a game console, an MP3 player, or a CD/DVD player, the X-540 can not give you surround sound; Instead, it gives you "Matrix" sound. When not used with a PC it compares functionally to the Altec FX4021.
There was an unanswered question about the cable length. The cables for this PC speaker system are: Front: 5 foot 4 inches, Center: 7 foot 4 inches, Rear 14 foot, PC cable: 6 foot 3 inches. For a PC surround sound system, this might be enough. Audio enthusiast say that including more cable introduces sound lag.