I have all the psd files and nothing I can edit them with so I went photoshopping. Sorry I could not resit that temptation. I find that I can usually be quite satisfied with an older version of most software. Because of the name changes I can't quite figure out what the current version is. It looks like 6.0 is the lowest upgrade path to the current version which I thought was 9.0 except now it is CS. I just want to edit all image files including psd and be able to easily slice large images into web sized chunks for web pages. I am converting from another MS graphics program so the lower the learning curve the better. I have green to give for this one.
I'd go with version 7 if I were you. I believe PS 6 doesn't have the patch tool, healing brush, advanced brush settings, and some of the blending styles that I think are essential. These tools probably seem insignificant to you because you're new to PS but you're probably going to want them eventually. However if all you're going to do is basic photoshopping and don't intend on learning anything advanced then maybe PS 6 will suit you fine. Also, I think you'll find with PS 7 that you can find more tuturials as it has pretty much the same features as the CS versions.