The TechZone has posted a review on the Z-5450 speakers.

I decided to try the Z-5450s with a few PC games and also with a few Xbox games. On the PC side, I gave it a run with titles such as Half-Life 2, Doom 3, and Battlefield 2. Gaming with these speakers was a delight to my audio senses. The surround performed beautifully and the precision of the sounds coming through really enhanced the overall gaming experience. The results were the same when I switched it over to the Xbox. I only chose titles with support for Dolby Digital and ended up playing half of the games in my collection just to see how much better they would sound. Before I knew it, half my day was gone and I didn't regret it one bit. Now I can't wait to receive my Xbox 360 so that I can enjoy what next-gen gaming will sound like on these speakers!

Logitech Z-5450 Digital 5.1 Speaker System Review