I'm a very recent switcher (about mid-January), and as soon as I got all my data off the PC and onto my Mac, I reformatted the drives and installed Linux on it, turning it into a fileserver on my local network
I transferred my Photoshop license from Win -> Mac, and Lightroom is dual-licensed by default - those are my 2 major apps. I got the new home edition of Office from MacMall (It's worth having Word to be compatible), and it works great, just like the windows version did.
After using OS X for 1.5 months now, I'm loving the ride, even though I don't yet know all the in-depth tricks, tips, and cool config options you can do with it, but I'll learn (any links would be useful too

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I'm so much more productive with spaces, I'm finally making regular backups automatically (time machine)....there really is NO downside to OS X, and I don't plan to ever go back to windows if I can help it (certainly not on my home system, anyway!)
I've nearly got everyone in my family convinced to get a Mac as well - no spyware, no viruses works *very* well as a motivational tool
-Bryan