Photography Student (Starting Out)

[_SJ]

For the past several years I've taken all my pictures with a Nikon Coolpix 950, it was my first digital camera and I never had any real need to upgrade it. However, I'm now about to start a photography degree course and feel I should be using something a little more professional so I've been looking into buying a new camera. They have some Nikon D70 available for use on the course but I want a camera of my own that I can carry around with me and use for all purpose shooting.

Budget:
About £500-800 including acessories

Size:
I'd like it to be fairly portable, I was very happy with the size of my 950 but I'm prepared to go for something a bit bigger.

Features:
5-6 Mp should be plenty.
Standard zoom is fine but more would be a nice bonus.
Image Quality: 7?
Manual controls would be good.

General Usage:
I'll be using it for everything - Wildlife/landscapes/portraits/theatre
I probably will want some big prints from time to time
I take pictures for a theatre company so I will need to shoot some indoor/low light pictures.
I don't take many sports/action photos but wouldn't want to rule it out.

Misc:
I started off looking at the Canon S2 IS/Panasonic FZ5 but have now moved on to considering the Pentax *ist DS/Canon XT/Nikon D50 and I'm open to other suggestions.

Thanks a lot for any help/suggestions.