you can get a trial version of PS from there website, personally i use LightRoom which is another adobe product, you can also get a trail from the adobe website too.
they can also be found in other places if you know where to look!
a few other smaller easier programmes to consider
google paccasa
irfan image view
paint shop pro
and the gonk, pretty much like PS but totally free.
I use Photoshop CS4. It's probably completely unnecessary for me to do so, and I'm sure that one of the free products would be able to handle my needs, but I got used to using Photoshop very quickly and can't be arsed to learn owt else.