To be honest, 2.1 PC speakers are fine for gaming, even the cheap ones. When it comes to music though, the cheap ones are rubbish and the better quality ones don't hold a candle to a decent pair of stereo speakers such as the Q Acoustics mentioned above. It depends where the user's priorities lie.
If you wanted something for mainly music with some gaming, then I'd suggest getting stereo speakers; but for mainly gaming with a bit of music, then the better 2.1 PC speakers are worth looking at.
I've got some stereo bookshelf speakers connected to a small amp. If I used them mainly for gaming, then I could probably switch them for a 2.1 set and wouldn't be any worse off really. The vast majority of use though is music, which is an entirely different ball game. Metaphorically speaking, I'd rather cut my own arm off than swap them for 2.1 speakers.
There are a lot of crap 2.1 speakers though, that can't do any music justice unless it's all just one bass line. £50 buys rubbish, £100-150, something much better. The slight problem is that cheap rubbish 2.1 speakers are ten a penny, whereas as better quality ones are few and far between.
Harman Kardon Sounsticks III are very good, but the styling is a stumbling block for some people; you either like it or you don't.
Edifier C2XD are decent. They got good comments from 2 forum members who bought them after their Corsair SP2500 speakers failed.
A few other good ones have long since disappeared and either haven't been replaced, or were by something a bit too expensive, such as Acoustic Energy Aego 3.
I suppose though you probably can't go far wrong with any £100+ 2.1 speakers, as long as they are reliable.
Using stereo speakers for gaming, coming from 2.1 speakers, I think you'd find them somewhat hollow. Another forum member found this after he bought some Ruark MR1 speakers to replace a cheap 2.1 set. Fantastic for music, a bit hollow when it comes to gaming.
