Remember that when choosing a digital SLR camera you are getting the whole package (lenses, accessories etc.). Each manufacturer offers accessories that are compatible with its brand of cameras. Therefore moving to another manufacturer, might not be so simple.
Digital SLR cameras are intended for enthusiastic amateurs and professional photographers. Compared to compact digital cameras, digital SLRs offer many options and manual settings for advanced photography. They can be purchased as SLR kits including body and lenses, or lenses and SLR bodies are also available separately.