If you are upgrading and already own Canon or Nikon lenses, you should stick with your brand, the differences between these two cameras should not be enough to cause you to switch.
12.3-megapixel DX-format CMOS image sensor
Outfit includes the 3x AF-S DX NIKKOR 18-55mm f/3.5-5.6G VR lens with image stabilization
D-Movie Mode with sound; record 720p HD movie clips
Vari-angle color 2.7-inch LCD monitor; one-button Live View
Capture images to SD/SDHC memory cards
A remarkable blend of simplicity and highly advanced D-SLR capabilities, the compact and powerful D5000 offers breathtaking 12.3-megapixel image quality, along with a flexible, Vari-angle, Live View monitor for fresh picture-taking perspectives. Nikon's EXPEED image processing further enhances performance, contributing to split-second shutter response and continuous shooting at up to 4 frames-per-second to capture fast action and precise moments perfectly.