DSLR and pixalization

[Masha]

Hi Marko,

I got a canon t2i for new years and have been playing with it and so far even on auto, it beats point and shoot 10 times over so we are very happy but i noticed that sometimes some parts of the image get pixalized.

For example i may have an amazing up close photo of monkey (my cat) with the 18-55 lens and it looks amazing -- every hair is defined on his head and face and when the photo is viewed in 'paint' in its actual huge size it looks great but if i view it with any of the regular programs like windows photo viewer, etc. it would bring it up in normal screen size and then his whiskars get pixalized...

this also happens if i am viewing it in paint and decide to zoom out to have the photo fit the screen, it gets pixalized as well... any ideas what i am doing wrong?

I want to be able to post these great photos in a normal size on pets.ca and face book, etc but when i have them in a normal size they looks pixelized...

Many thanks!!

here is an example: