I listened to enthusiastic claims much like yours twenty years ago and made the very expensive switch to a Mac II. I waited a year for the RAM I needed. I had it for about five years and endured that little bomb more times than I care to relate. I couldn't get a good CAD system (Pegasys, what a piece of crap). As to getting boards for various machine controls and instrument interfaces, make me laugh. Not only were there few, they cost a fortune.
I was forced to make the very painful switch back to Win. I lost a lot of work that I never recovered.
About the only thing I could say positive about the Mac was file efficiency. Now that I have another fifteen years' work to lose, no way.
Yeah, I hear ya.
Macs are hideously overpriced, and expansion capabilities are limited or non-existent.
You are better off with Windows, then.
I would stay away from Vista, though. WXP or W7 are the way to go, and you should get the Pro or MultiMedia versions.
W7 does not provide an email client, except through their spyware infested web interface, so you will want to consider using your ISP’s email client or use something like Thunderbird, if you prefer local clients.