I wrote a little bit of my new love.. Fedora Core 8 on a compaq laptop.
It works really well.
If you compile packages from source and need various versions of gcc, it's a little bit of a pain.
I suggest using KDE vs Gnome as your desktop to maximize space and usage. I set up Win+Esc to switch between the desktops, each has two terminals dividing the screen in half vertical wise.
I preffer gnome-terminal.
I would say what's much more important then the flavour of your posix system, is the hardware you choose.
If you get an older IBM thinkpad, you are blessed by the penguin. Do NOT get a cheap Dell, you will be cursed by m$.
ps, i would suggest against mac. I love apple, we set up clients on mac- love it love it- I would not code on it. mac osx is built around unix, whatever that means.. and you're not going to be on ext3.
I would imagine the ideal world would be to have the time, money, and stomach to run linux on a mac.. it's been done, and done well.