I've gotten a lot of questions in the last year about photography stuff. Among the most common I hear is "What (camera / lens / voodoo magic) do you use?" Most of the time, I'll regurgitate a shopping list of unnecessary equipment that I may or may not have and be on my way. Deep down I'll get that urge to scream out "Stop asking the wrong questions!" Instead of asking about what was used, ask how I did something.
I'm just an amateur that is making an effort to not suck entirely, but I've already crossed the boundary where I know that equipment will only do so much for you. Which camera should you use? Whichever one you know how to you (or are willing to read the manual). If you really care about trying to take purty pictures, then that ability will most likely come from lots of reading, lots of looking at pictures, and lots of practice. I've taken a few good and a lot of bad pictures with my new 5DmII. I've taken a few good and a lot of bad pictures with my 450d. I've taken a few good and a whole lot of bad pictures with whatever other point and shoots I've had on me over the years. Getting fancier gear will let you push the boundaries if you know what you're looking for. It will also let you create expensive garbage if it's underutilized (why spend four grand on a camera just to keep it locked on full auto??)
I spent a few months in Costa Rica in the beginning of 2007 and the only camera I had was a little Panasonic point and shoot. It was nice being able to travel with a backpack full of food and clothing rather than lenses like I'd end up doing today. Digging through those old files, there are quite a few images that I don't find entirely offensive. Come to think of it, some of the only pictures of mine that I've got hanging in my apartment are from my time traveling with a pocket sized camera. Just one example of squeezing decent results out of very little.
So fair warning, friends - next time I get asked what camera or lens I used in the creation of an image, I'll be responding with stories about magic devices being blessed by Marie Laveau or some other nonsense. My stories will entertain me and help you just as much as a serious answer up until you start asking the right questions. Until that welcome moment...