Ideally there should be no issue running either on a Windows 8 system. CS6 is the most recent version and been tested and confirmed to be compatible with Windows 8. CS5 will work but you might have to use the compativility mode. If you search this forum using the Ask A Question field at the top of the forum page, and enter CS5 Windows 8, you will find several results supporting it.
As far as the graphics card goes, I am not tech savvy enough to answer beyond remembered hearsay, but I believe a gaming graphics card is one of the better choices all around.
