I recommend the Nikon D40. If you get the D40 from Amazon, it is only $450, with a 18-55mm lens (an excellent lens), and because it is so cheap, it would give you some extra cash to buy lenses, flashes, etc… and thats what will really affect how good your pictures will be. http://www.nikond40.ca/

The D40 is a great camera.

One thing about the D40 to keep in mind, is that if you are used to the second lcd screen on top, (for aperture, shutter speed settings, etc.) than not having it on the D40 could be quite annoying, if you are not used to using that screen, than I do not believe it would be a big problem not to have it. I do not know if the sony alpha has this.

Go to a camera store, such as Best Buy or Henerys. Both of those stores will let you handle the cameras, and test them out. Test out the D40 as well, and see which you like better.

Any other questions, feel free to send me a message.
zlh
References :
D40 Information:
nikon site: http://www.nikon.ca/en/Product.aspx?m=17040
cnet: http://reviews.cnet.com/digital-cameras/nikon-d40-w-18mm/4505-6501_7-32156779.html
kenrockwell (great site): http://www.kenrockwell.com/nikon/d40.htm

The Nikon is the entry level DSLR that is the most popular and puts you in a spot where you can start building on one of the largest camera systems in the world.

http://www.jdpower.com/electronics/ratings/digital-camera-ratings/dslr

So you did not shoot some shots using the D40 with the AF- S 18-55 mm ED lens?

On the practical aspects of choosing a camera, the Nikon system has lenses that will work on most of their cameras bodies … since 1959.

Sony bought the old Minolta line and lenses older than about 20 year old, will not work, whether in manual or auto modes
References :
digiPro