Was in the same place a month ago, here is what I wish someone told me.

- You can move a file, just "copy" and then press option when "pasting"

- Command + Delete is deleting a file (del on windows)

- Rename file is Enter (f2 on windows)

- Command + tab actually works as intended

- Fn + Delete = del key

- Home, End, Pg Up, Pg Dn - different, you'll get used to it

- Learn Vim and Linux, as you'll use the terminal a lot

- Installing stuff is a bit weird - dragging the icon to the Applications shortcut, dmg files basically look like a virtual "drive" that you can eject

- No easy way to maximize a window, really, you need a 3rd party app

After getting used to the little quirks, you'll get used to the stability, and speed. Windows 7 is not a bad OS, but for some reason me and my wife fight over the MacBook Air more than on my Lenovo Thinkpad...