Well, the Mac obviously has Photoshop and Dreamweaver if you want to keep using those.
Pixelmator is a very good Photoshop alternative – not quite as powerful, but FAR cheaper (I think only $60 or so?) and it integrates with OS X much better. For stylesheets, CSSEdit is amazing – about $40 I think and there’s nothing quite like it on Windows.
Smultron and Taco HTML Edit are both decent HTML editors. Smultron is free and handles a bunch of different languages. Taco is about $20 but is geared towards HTML specifically.
Cyberduck is a very good free FTP utility. Check out Transmit if you’re looking for something more advanced.
There’s also Coda for "one-window web development" – edit HTML/CSS/etc., preview live and upload to FTP all within the same app.
You might also want to check out RapidWeaver – it’s a visual editor where you pick a theme you want for your site, then fill in the content. You can get an entire site up extremely quickly with it, but at the same time it’s also very flexible so you can change quite a bit with the built-in themes.
Sorry I don’t have links – Google any of these with "Mac" and you’ll find them within the first few results.