You can do anything Powertracks can do (and MUCH more) in GarageBand. And, if the need arises, you can get Logic (at about half the price that Cubase demands) and it will open GarageBand projects as is, allowing you to take them further if needed. GarageBand is basically Powertracks and Acid, combined with a bunch of good quality free VSTi's and loops. All for FREE...

The problem is, you can't find something the SAME as your favorite applets from the PC. But you can sure find something that will allow you to do the same thing, albeit in a different way. And often a better, more elegant and advanced way. But, bottom line is, if Powertracks were so important, (or any other favorite PC app), you can run it on a Mac! Depending on the program, you might even be able to run it without rebooting...

I know that you can't come straight over without some adjustment period (Lord knows, I'd need one, too!), but after the adjustment period, at least you are in the hands of a computer company that takes OS stability and internet security SERIOUSLY. You can for sure forget everything you had to learn about spyware and virus paranoia