Two Dogs, if you are heavily into photo editing, or into heavy photo editing, (or video editing, for that matter) then 2GB of RAM will make life easier, for just a few dollars more. Just upgraded myself from 1GB but because there are now, often only two slots on the Mobo, you don't end up with 2 x 512MB sticks of DDR400 leftover, like ermmm.... Me.
Mind you, I am sure that I will end up using or losing them somewhere...
Conan