Confused as to which camera I need? And what camera do you use?

I'm thinking of upgrading my camera to a new one. My budget's up to £500 although if it was cheaper I wouldn't complain. I've been looking around at a few different models, but I'm not sure what I should be looking for. While I want a camera with extremely high quality images, I'd also like it to focus well.

Would a DSLR or a digital camera be more suitable?

A couple of examples of what I mean.

Nikon D3100 14.2MP DSLR
Canon SX30 IS

Which camera do you personally use?
(And final question, sorry! Is it difficult to get the hang of changing camera lenses or is it pretty simple?)

Just for reference a dslr is a digital camera.

I use two, the Canon 1000D and the Canon 500D, both dslr cameras and both are very good.
The 500D however does very nice video also.

I recommend them both for quality and performance.

First… The simple question… Changing a DSLR lens is pretty simple: Remove the camera body cover, remove the rear lens cover, line up the lens and body alignment dots, insert lens into the camera body, twist lens 1/4 turn until it clicks in place. Press lens release button, twist lens 1/4 turn, remove from body, put covers on.

If you are wanting a camera that does all the "thinking" and focusing for you, then look at the P&S (including the "bridge" or advanced P&S) cameras. If, on the other hand, you want a camera that you can have total control of its operation, then get a DSLR.

There isn't much point in spending the extra money for a DSLR and the additional lenses if you are just going to use it as a P&S camera. Consider things like the Canon G12/SX30 IS or Nikon P500/P7000

I use:

Canon 1D Mark III
Canon D30
Canon SD870 IS
Various film cameras
Sony video camera

I've always used a SLR when we had rolls of film. When the digital cameras came in I bought one thinking it would be great to have an easy to use camera with a 3" screen on the back. Everything was fine until I tried to shoot in sunlight & that screen showed nothing. I just held the camera up, snapped some pix and fixed them later before I printed them.

My way of saying next camera will be a digital single lens reflex. A back screen is nice, but to really compose good pix you need a viewfinder. On a SLR you are seeing what the camera lens is seeing. I think the modern SLRs may have both screen & viewfinder.

Another advantage of a DSLR is the capability of changing lenses. You can also get filters to put on your lenses. Changing lenses is easy. There's usually a button on the lens - press it, give the lens a slight turn, and you're ready to put on a new lens.

Can't advise on which camera. Both Canon & Nikon have been well made, top brands for years. Important thing is to hold it in the store, look through the finder, feel its weight, etc. Find the one that feels right in your hands. Good luck in your search & have fun with your new camera.