Which one will you choose as a beginner?

Canon 550D or Nikon D3100

The one that feels better in your hands.

To continue Andrew's answer - Nikon, Sony, Pentax, Olympus, Canon etc all make great cameras. Go to a local camera shop and try them both out. Also handle the Pentax K-X

Before you make your decision, consider the Nikon D3200.

At the present time, it is the best entry-level DSLR for a beginner.

But that is sure to change over time.

I would Recommended the newer upgraded Nikon D3200 camera

Product Highlights

24.2MP DX-Format CMOS Sensor
EXPEED III Image Processor
3" 921K-Dot LCD
AF-S DX NIKKOR 18-55mm 3.5-5.6G VR Lens
11-Point Autofocus
HD 1080p Video
Live View
Up To ISO 12800

Nikon D3200 camera features a wide ISO sensitivity range from 100-6400, which can be increased to as high as 12800. Get great shots and clips under various lighting situations with low noise. Capture full, broadcast-quality 1080p HD video at 30, 25 or 24fps, and 720p video at 60 or 50fps. The optional ME-1 Stereo Microphone (not included) provides crystal clear stereo sound to accompany your crisp video. You can shoot up to 4fps at full resolution to catch those precious moments missed by other cameras.

A great camera

Hope it was an help

As a beginner, maybe I would choose a cheaper one. A digital camera maybe. The Canon G12 is a good choice. My cousin has it and I'm very much amaze of its performance. Ours is the cheapest model of Canon but it does good too.