I have this Logitech Z-2300 2+1 speakers set for some years now and it has never stopped to amaze me. The sound is clear yet powerful and they are perfect for both immersing into the worlds of PC games and listening to music.
The L&R speakers are small enough yet they produce impressively deep sound. Paired with a good THX Audio card, how your PC sounds will never be the same! They come with a (removable - but be careful) front mesh which makes cleaning them easy.
The subwoofer is powerful and one has to really play with the sound card equalizer to be able to hear any bass distortion.
What I really liked was the wire remote which includes Power, Volume and Bass controls - and sports a handy earphones outlet. This is very convenient since most earphones do not come with long enough cables to comfortably attach directly to a PC case outlet.
My only complains would be that the remote is attached to more than one wire of unequal thickness and of not enough length (you will be able to keep it on your desk only if the PC tower is just below and the subwoofer nearby). Moreover, the subwoofer is too tall to fit under my desk (at 11inches [28cm] it does not fit under the drawers on the side I would want it) so I had to keep it outside my desk, increasing the number of visible cables. But that is a small price to pay for such great speakers.
For best results try them with Gothic Rock or Vocal Trance. Let the sound absorb you and the vibrations move you.