great link and info, thanks!
An old computer rule: No computer can process faster than the slowest device involved in the process.
Have fun. Unless you're really sure about your workflow, I'd think you're probably better off with a Mac Mini than anything else. They go fast enough and have Intel Graphics, which are good enough for PS. You can pick your monitor from a much wider selection, including craigslist. You might be surprised what you can find there.