I was in a similar dilema to you and went for the new Sony A100 DSLR. Much has been made of noise at high ISO but the magazine reviews seem to rate it favourably. I have not had any issues with it too date but then I am a complete amateur when it comes to anything manual. Having said that, the picture count with my Ixus is now over 20,000!!!
Jessops are doing the camera plus kit lens for £599.
http://www.jessops.com/Store/s35784/...tId=481&comp=y
The new Nikons/Cannons are probably a tad over your budget. My other option was the D50 but I liked the idea of the in-camera anti-shake, as it should make future lens purchases cheaper.
Trust this helps.