Which Eclipse package should I download for PyDev?
If you just plan on doing Python dev, I'd just go with Platform Runtime Binary.
After that, I'd follow the instructions http://pydev.org/download.html and http://pydev.org/manual_101_root.html to install PyDev.
I use the same setup for Python development. I also have the RadRails plugin for Ruby on Rails development.
Assuming Python, and nothing else - I would just get the "Runtime Binary" edition of Eclipse, and add the PyDev extension. That way Eclipse starts up lightning fast, consumes less memory and generally gets in your way less. On top of that, you can always add in whatever extensions/plugins you find you need. The runtime is generally around 50MB, instead of the usual 100+ for the SDK or other versions.
You can always find the latest version here:
http://download.eclipse.org/eclipse/downloads/
At the time of this posting, that would be 3.6.1:
http://download.eclipse.org/eclipse/downloads/drops/R-3.6.1-201009090800/index.php#PlatformRuntime