Acoustic Energy Aego M and Corsair SP2500 are both very good. Aego M have been replaced with the more expensive Aego 3, and it looks as if the SP2500 have been discontinued for the second time.
If you can find Aego M or SP2500 then either would be a good choice for the right money. Aego 3 are £200 and not likely a huge improvement over the Aego M, just a different style with added Bluetooth connection. Whether any PC 2.1 speakers are worth £200 though, I don't know.
Doesn't leave much choice at all really when it comes to decent 2.1 speakers. There's Harman Kardon Soundsticks III, which are very good and a decent price for around £110, but I'm almost certain the looks will put you off as it does most people. Shame really, because they are very good speakers.
Not sure what other 'good' 2.1 speakers there are.