If you want to go to a Mac system, do a search for PearOS. Here:
http://pearpc.sourceforge.netThat will allow you to run a Mac oerating system on regular PC hardware

.... until of course you decide to buy a Mac

You might also want to consider the Linux options. You could probably set up a surprisingly well preforming Linux box on your existing hardware. Between the programs 'gimp' and 'sodipodi' and a few others, you can do just about anything with graphics (Window$ versions exist too).
In other words, Adobe and Corel aren't the only options.
Unless you're editing HUGE graphics, your Win machines shouldn't be brought to a crawl unless there's something else playing a factor. Such as wrong swap file size, too many running services, or spyware/virus.
Even if you run Norton or Macaffeefefeee or whatever their name, you aught to download and run the latest trial version of Kaspersky antivirus.
http://www.kaspersky.com'cause it's known to uproot virus variants which Norton and Mcaffee don't (such as the .h variant of 'paylap').