I have a wide-screen 17" Vaio, and it was a total pain to travel with. Heavy to carry around, difficult to use in Y, slow boot time because I have so much stuff on it, etc. Now that Wi-Fi is fairly standard, I invested in a Toshiba Mini. While they are not overly powerful, you do fairly well with a web browser open and 1 other application (i.e. Word or Excel). They are very light, have enough battery power for any domestic trip, boot quickly, and once you get used to the smaller keyboard, they are easy to work with. I just put whatever files I will need on a jump drive, and I'm ready to go. I also pack my cables in my luggage to save some space. The one drawback is that if you want to watch movies, you have to purchase (not a big deal) and carry (more of a pain) an external DVD Drive. You can also generally get away with slipping these in the seatback, as they are small enough to be covered by by a magazine.

It has become my second favorite travel accessory after my n/c headphones.