Magnify or zoom a selection

This link should work for the image, and you don't gotta worry about too much traffic (I hate when they shut off access to sites or files for too much traffic. grrr) Anyways, this is Caddy's original file:
http://0ut.home.comcast.net/mustangmag01.jpg

Some suggestions and/or examples of what's already been suggested:

Using Spherize (plus a touch of layer styles for highlights):
http://0ut.home.comcast.net/mustangmag02.jpg

Or you could try using Liquify (make the brush size larger than magnifying area then use the Bloat tool):
http://0ut.home.comcast.net/mustangmag03.jpg

Or here's Liquify to create a flawed (warped) lens, like a cheap plastic magnifying glass or something:
http://0ut.home.comcast.net/mustangmag04.jpg

And naturally if you don't use the effects as heavily as I did in these examples then your pixelation won't be as bad.