Hi 'Tatty'
I have same amp, and bought the Q Acoustics 1010i speaker package (Bought for £405 but I can only find them for £450 recently). With sand filled stands, and granite plinths, as well as a mains conditioner (tacima CSC929, I think) the sound is very impressive.
Obviously, your budget is higher, so you could exchange the front 1010i speakers with the 1030i floorstanders if you have the room.
My alternative suggestion would be the TANNOY MERCURY F1 CUSTOM 5.1 SPEAKER SYSTEM, as sold at superfi for £700. If I'd had the money at the time, I would have bought this set rather than the Q acoustics, just cos I have had Tannoy speakers for years, and rate them completely.
http://www.superfi.co.uk/index.cfm/page/moreinfo.cfm/Product_ID/3322
If you have limited space, maybe look at the new KEF eggs (2005.3, I think) They are the same price.
http://www.superfi.co.uk/index.cfm/page/moreinfo.cfm/Product_ID/4360
I have to admit, though, I have a mate who has the original KEF 'egg' system, and his sound is completely different to my traditional shaped speakers. Both sound great, but it would depend on personal choice which is better.
Hope that helps.....