Meet The Contenders
In this comparison, the Logitech Z-5450 has the edge in connectivity. This is the only system that is equipped with digital audio inputs, and that feature is significant. It's a really notable omission from the Creative Gigaworks G550W system, although the Altec Lansing FX5051 can get away without it because they're USB driven.
The Z-5450 also has the lead when it comes to sound processing features: they can decode Sony Digital DTS and have a Dolby Pro-Logic 2 decoder built in.
The most distinctive selling feature of course is the wireless functionality. The Logitech's rear surround speakers are wireless, but only in the sense that they don't need speaker wire from the amp - each of the two rear satellites has its own wireless receiver inside, but still requires an AC power cord to be plugged into a wall outlet. Depending on the power outlets available in the room, this might be more or less convenient than running conventional speaker wire in the first place, which is definitely something to keep in mind when considering a purchase.