RE: screens, a lot of the "super-duper" claims of resolution refer to the output to a normal monitor,
not the laptop screen. From what I've found, most laptop screens will only support up to 1024x768 with 16 bit colour. Anything over that, read the .pdf specs, as it will most likely refer to output [to a monitor]. E.g. XGA, SXGA, UXGA. In this vein, look at graphics hardware. ATI Rage Mobility and GeForce 2 GO are the newest, and are very highly rated. Try and avoid any "shared memory" graphics cards, as they use system RAM (and not terribly efficiently) instead of dedicated, onboard memory.
Size-wise, bear in mind that the screen is one of the largest battery drainers, so depending on how long you'll be away from mains supply, it's important to get the smallest acceptable for your needs. That said, power management utilities do compensate by dimming the screen when on battery power - yet another thing to check in the shop! You could go the way of "hot swappable" drive bays, which accommodate a second battery in place of the CD/DVD drive, but that adds to the cost.
On a different note, whilst browsing the other day a shop owner I've known for years warned me off buying a laptop in the near future, as there are some "big changes" coming out in terms of hardware and prices. Prices of existing models/stock will be cut, making "bargains" easily available.
In his words "I just know that if I bought a laptop and found something much better for the same money soon afterwards, I'd be really pi$$ed off" Whether or not this will turn out to be true is another matter, but the caution was given.
More than I planned to write, but it's not easy being sure you've got all the info you need
Cheers.