PhotoLine is significantly more affordable. Dated interface but the German brothers put out consistent updates, bug fixes and enhancements (even in the same version number range and so no extra cost until major version number change). Menu names for PS functions differ in many parts. Download the trial.
Take care, Mike
GIMP is free and has a lot of features. Some learning curve however.
Might also try free 30 day trial of PS Elements 11.
Just to be clear, what do you mean by; "can't load CS2"?
What happens? Do you get error messages? Does the media just not read?
Are you aware of THIS?
It is pretty much a case-by-case basis, but I do know people running CS2 on Windows 8 under compatability mode. More info would be helpful.