You've got a lot of options open to you with £1,000!
You're never going to get a definitive answer to the "which camera should I buy" question as everyone has different preferences. If you've got access to any older lenses that you could use that may well sway your decision towards brand. If not you've got a huge market to choose from.
If you're not sure what sort of photography you're interested in (and there is nothing wrong with being interested in lots of forms!) then I would suggest you start with a good range of lenses and see where you're interests take you. I learnt more from my first camera than I ever did from magazines, forums and reviews put together (and they're pretty helpful!).
For example, for your £1000 budget you can get the Canon EOS 450D with the 18-55 IS, 55-250 IS and the Sigma 10-20. The camera, 18-55 and 55-200 come as a twin lens kit (
here) for £683 and the Sigma is £389 (
here).
Thats a lot of kit but it covers a
lot of focal length! You could make it cheaper by going for the EOS 1000D.
For completeness (and to try to give you all the options in 1 simple go) you could also do the equivalent ranges from other manufacturers...
Nikon D3000 with an 18-55 VR (£394
here), the 55-200 VR (£234
here) and the Sigma again (£389
here).
Olympus... E-520 (the 400 series don't have image stabilisation built in so I personally believe the 500 or 600 series are worth the extra money) comes with either the 14-42 & 40-150 (£441
here) or with the 14-42 and 70-300 (£614
here) both of which leave you with enough money for the Olympus 9-18mm (£444
here).
Sony a380 with the 18-55 and 55-200 (£624
here) and the Sigma 10-20 again (£389
here).
All of these ranges are around £1,000 and, with the lenses, cover a huge range. Personally I am a fan of the Olympus system - I used to use it myself. The Sony and the Olympus certainly offer the best value for money of these 4 systems. They also have their image stabilisation methods built into the camera body, rather than in the lens like Canon & Nikon).
The Nikon is the most expensive system for what you get but it is the newest camera.
There has also been much debate about handling cameras. Personally, I would suggest it. If you're stuck between 2 or more systems then the ergonomics, handling, layout and even looks of the system might help you decide (there is nothing wrong with liking a camera simply because it looks nicer!).
Ultimately there isn't a whole lot to choose between them. Canon and the Nikon have the largest range of accessories but Olympus are constantly updating their products and Sony have pretty much the whole of the Minolta range of lenses to fall back on. If you buy the one you like the most you'll use it more.