every web designer I know swears by writing code from scratch. The problem is with apps like dreamweaver you get extra code tossed into your web pages, and that code is there so the application can decipher what you are doing.
There is a free open source version of dream weaver called NVU, and I am currently using it myself to re-teach myself web design (I haven't built a web page since around year 2000 and well technology has changed A LOT since then). I am already seeing myself ditching this app all together once I learn the ins and outs again.
http://www.nvu.com/
As for PDF files, OS X has a native print to PDF option. So you can be working in any application be it MS word, or open office or neo office, or text edit, or whatever and you can print your document to PDF which automatically encodes that file in portable document format.
If you purchase a new mac you should get a copy of iWeb which is Apple's own little web building application. I have not used it, but I do have a copy of iLife 08 sitting in my CD binder in my bag. It would be simpler than NVU but not as complex. That is just a guess, you will have to see for yourself.
As for web design I highly recommend two text editors,
textwrangler and
taco HTML. Both of these apps are sweet and I use them both. I do almost all my scripting in textwrangler now exclusively.
Some great apps for ripping DVDs are these two apps here:
http://handbrake.m0k.org/
http://www.mactheripper.org/
Of course the best media player ever works on every platform
http://www.videolan.org/vlc/
FTP servers
http://captainftp.xdsnet.de/cftp/description.html (i think this is pay for)
http://cyberduck.ch/ (this is free)
GIMP, a program comparable to photoshop and it is free
http://www.gimp.org/macintosh/
Neo Office, this is an office suite that runs natively in OS X unlike open office which requires X11 to be installed
http://www.neooffice.org/neojava/en/index.php
If you are a Linux user and miss all your old Linux BASH command apps, you can install them via Fink Commander, or Fink if you want the command line version
http://finkproject.org/
Audio recording application
http://audacity.sourceforge.net/
A fun DJ/Turn table application that runs smooth with iTunes
http://www.algoriddim.net/download/index.html
Back up and cloning software, netrestore and CCC (all of them free) a free boot loader for dual booting macs, a login window manager, etc etc.
http://www.bombich.com/
Tons of open source print drivers for printers
http://gimp-print.sourceforge.net/MacOSX.php3