Windows Photo Viewer Gallery has some very basic editing functions but there's much better software available.
The (free) image viewer which deserves a place on everyone's PC is Irfanview:
http://www.irfanview.com/
As well as viewing images there are some good photo manipulation options, although you might need to hunt around to find everything. (It's one of those programs where it really does pay to read the help files).
Serif PhotoPlus SE is also completely free, and offers some of the tools that programs like Photoshop have:
http://www.freeserifs...Plus/key_features.asp
The nearest thing to Photoshop though (which you can get for free) is GIMP:
http://www.gimp.org/
It takes time to learn how to get the best from it but for free 'serious' image manipulation it can't be beaten.
Lastly, Google's free Picasa software is widely recommended:
http://picasa.google.com/
Chris