In an effort to expedite your transition away from Windows entirely, may I suggest Pixelmator (http://www.pixelmator.com/) as a Photoshop alternative? It is a pleasure to use and has all of the core features of PS (compositing layers, tools etc).
I have Pixelmator, and I think it's a good 60% solution, but it's no Photoshop. For example, the other day I fired it up to make constrained rectangular marquee selections, and it can't do that. That doesn't sound like a big deal, but I wanted to select at a specific aspect ratio because I needed an image to fit in a specific box. There are lots of little things like that. Not to mention I've been using Photoshop since the 90s, so I'm very proficient with it, it does every single thing I need, and I already paid a lot for it.
There really is not a good substitute for Quickbooks Enterprise. And I forgot Regex Buddy. I downloaded Patterns off the App Store, but it's a poor substitute. Regexes aren't pretty, but if you are hacking on something a quick regex can do a lot for a little.
EDIT: I just re-read this, and thought it sounded a little too negative toward Pixelmator. I think being a good 60% solution in relation to Photoshop is a huge accomplishment, and that Pixelmator is great software. It is absolutely worth the money. It is a very competent intermediate image editor, and would be $30 well spent for anyone. The criticism is mainly directed toward the lack of some esoteric advanced features, and my curmudgeonly desire to have it work exactly like Photoshop, since that is how I have edited images for the last dozen years.
I love Pixelmator but I can't find any way to do nearest-neighbour resizing. Which I figured was the simplest thing to implement. Even MS Paint can do that.
