I use Sonar, but targetted at midifie creation. I import audio tracks from CD for comparative purposes during this process.

Is is pretty easy to use given the complexity of the problem. You can import audio or record directly then chop it up and cut and paste it around. There are also bundled audio effects but I don't know how good they are! Naturally the usual limiting factors are processor power, memory, and hard disc capability/capacity.

The downside of the PC is that you really need a non-budget soundcard as the quality of the converters on the soundcard will otherwise not be as good as those on the portastudio. I think you need to be looking at Audigy or better to be able to record seriously noise free, and even then the PC is not the most interference free device and you may get some occasional crackles (such as when the freezer kicks in).