ProTools vs. Ardour. Why spend the money

I've been looking at selling my Protools rig and going completely Open Source as far as software is concerned. Why? Because I am tired of being held hostage by the overpriced software and constant upgrades that are draining my bank account. So now we are looking at Microsoft Vista as the next so called *state of the art* operating system. So how much of my hardware and software is Vista going to break? Every single version of Windows has broken stuff that worked fine in previous versions and the manufacturers tend to orphan the support for their older hardware and software because they want to sell us new stuff. Quite frankly I am sick of the whole thing which is why I have been looking at some of the Open Source alternatives. I have been looking at Ardour running under Linux and I really can't see anything that Protools can do that Ardour can't except maybe my UAD card, which admittedly is a biggie.

Here is a link to the Ardour web page.

Can anyone level set me, tell me I am crazy or encourage me to go forth and be a pioneer? My main concern is getting clients, seeing as 8 out of 10 want a Protools based system. Thanks for your consideration.