The other day, I had to load up a DVD to install TurboTax and realized that it had been a solid year since I'd last used the DVD drive -- the last time I had to install TurboTax. For a laptop, this is now the #1 question for you: do you need a DVD drive? If not, then you've got the MacBook Air and a variety of "ultrabook" PC clones from Lenovo, Samsung, and others. Many of the ultrabooks comes with SSDs as well.

If you're planning to go with the PC side of the house, then you also need to decide whether you want a touch screen. Windows 8 ultrabooks tend to include some sort of flippy screen, turning your laptop into a tablet and back again. This sort of thing might be useful if you fancy yourself occasionally using your laptop as if it were a tablet (e.g., watching movies, playing casual games, etc.).