It's said the worst thing you can say to a photographer is 'gee, great photos, you must have a good camera'. Poor quality camera gear will make things hard but good quality gear doesn't make a good photographer. Many people get wedded to different brands too and the reality is it doesn't matter whether you like Canon, Nikon, Pentax, Olympus or any other brand. What matters is the quality of the lens and in the case of digital the sensor. There are some basic functions that are valuable with cameras - depth of field preview, exposure lock, different metering modes, continuous and single autofocus, manual focus, and various exposure modes (fully automatic, aperture priority, shutter priority, program and full manual).
Likewise with a flash there is some key functionality to look for - the ability to swivel up and down and left and right and the ability to change the power output. Bonuses are diffusion panels and a catchlight panel.
Whatever gear you buy though, make sure you invest in learning to see firstly and then understanding composition.