For web design, the limitations of Linux... aren't limitations at all. If you need a rapid web layout program there's Kompozer, and to supplement that you have a ton of terrific open source html and css text processors.
A CMS is a wonderful thing, but really should only be used if you are REALLY going to USE it. If you're making an e-commerce site or an artist's site - it's ridiculous overkill. A CMS is what you need for an organization's website or a web2.0 community website, one with a great many content creators. That's not just any website. And to work with a CMS properly, you still need to master html, css and maybe php.(I confess I don't yet know php).
Learning to code html in a text processor, that's what professionals do, honest. And if you work at it and get comfortable creating sites with Linux - once you get back to using Dreamweaver, you'll find yourself MUCH more capable with it.
Me, I'm a graphic artist and Illustrator. My gripe is that the open source alternatives for Illustrator...are terrible! And Gimp only supports web graphics well, it features no cmyk, lab, multichannel or halftone bitmap color models.
So for what I do best, I'm going to have to save up and buy a mac or windoze box and see if I can get the adobe apps I need. Why Adobe doesn't port their software to linux/unix I don't understand. If I could run the adobe CS suite on Ubuntu say, I've recommended computers and operating systems to employers often and I'd love to be able to recommend Ubuntu for design studios....