Hey Ant;
I'm a Canon fan so I'm kind of biased.
At that price range, I would get the
Canon Rebel T1i
At 15.1 megapixels, it has live view, 1080p HD video, and a descent lens. I have had great results with Canon. They supply you with software and great technical support if you require it They have a nice website for firmware updates for your camera. Be sure to look into a UV filter to protect the front of the lens, a descent carrying case, and a descent amount of memory, especially for this one since it does do video and is 15Mp's. Download the manual from Canon's website and look it over too to view the operation of the camera and it's capabilities.
The
Canon XSi is the predecessor of the T1i, so is a little cheaper. It still has live view but no video and 12.2 megapixels. Still a very descent camera for the money and certainly better than the XTi that I use for the majority of my pictures.
Nikon makes great DSLR's too and shouldn't be discounted. Once you choose the brand it's tough turning back as lens are not compatible with each other if you choose to buy more lens as you develop more into it.
You're relativley close to B+H so I would pop in there, they apparently have a nice hands on approach to you trying out the various cameras.
Just a side note, even though some might be cheaper than B+H (I don't have stock in them) they may not be authorized dealers and therefore warranty may be an issue. Imported versions will naturally be cheaper but they won't tell you that unless you ask. Imported cameras are the same in every way, just the warranty is not and you would have to take it back to where you bought it from instead of sending it into say Canon...
Good luck with your choice.