I got some Bose speakers for me setreo in me bedroom and the sound quality is un touchable, clear bass and just pure excellence. But there not worth the crazy prices they come at.
The best PC speakers are Altec Lansing in my opinion, but Harman Kardon are excellent for PC too. The more you spend, the better they'll be basicly. I wouldnt go too crazy on pc speakers though, £40-£60 for some 2.1 speakers is more than enough. Maybe have to speand around £80 to get some quality 5.1's.