You and I have different needs for a computer it seems so model suggestions are not going to happen from me (for one battery life is of absolutely no concern to me).
If a desktop replacement is not your desire then strike alienware from the list, while most of their stuff is great and well designed it is almost invariably high end (the buyout means a few mid range things appeared but not much and even then it is still expensive).
Sony, my current laptop is an older Vaio (k315b) and it served me fairly well. it is prone to overheating (and so dropping the clockspeed somewhat chronic) and the drivers were only updated once nearly two years ago (
http://www.omegadrivers.net/ serves me well though). Their screens they tend to come with are very nice as far as laptop screens go (they use the same stuff as the PSP screen) although similar screens are available now.
HP, they do middle of the road things most of the time and their laptops are no different.
Dell, they work well enough although you can do better.
Samsung, before the Vaio was beaten out of my insurance company I had a Samsung machine and aside from my hand built desktops it was probably my favourite machine I have had ever: well made, drivers updated, nice design. This was 2 years ago though and things may have changed.
Local retailers, you may pay a bit more than with someone like dell but if done properly it is so worth it. These retailers usually do not lock down the BIOS as well which is nice.
General advice
Ports, a lot of laptops have no parallel or serial port nowadays which may be a concern (you can get USB adaptors for a lot of things: PS2, serial, parallel). Most come with firewire/IEEE 1394 but not all.
USB ports, I have seen laptops with as few as 2 ports which is useless for me: mouse, printer, USB stick, card reader, external drive, scanner are just a few of the USB devices I use day to day basis and there are numerous other devices I may encounter with USB. Not some much of a problem nowadays but make sure you have USB 2.0 support enabled (some older ones are locked at 1.1 and as the BIOS is invariably locked down you can not enable it)
Graphics, most laptops have shared memory between system ram and graphics and rather weak graphics cards.
Hard drive, one of the major speed limiting parts of a computer and some makers stick slow (if fairly large) drives in as a cost cutting measure: be wary.
CPU, my current one is clocked at 2.93 GHz although the fact it is a wimpy processor with 256kb l2 cache I suffer under intensive loads. As for 64Bit and dual/multi core 64 bit is way overrated (some stuff supports it but it only matters for a 64 bit OS) and dual/multi core is useful but not the be all and end all some make it out to be.
Memory, Office work invariably means the need for 90 apps open at once and graphics is a well known memory hog so I would say a gig of ram is what you are aiming for. Under no circumstances drop below 512.
Drives, I highly suggest a DVD (re)writer (make sure it is at least +/- but speed is not all that important), dual layer is a worthwhile investment if you like to burn a lot of stuff.
Cooling, nearly every laptop I have ever seen has cooling issues so try and see what happens when one has been running for a while (if a shop opens at 9 come at 4 in the afternoon etc and see how the comp performs having been running for a several hours). A lower clockspeed will help here mind as will not going for the smallest machine available.
OS, Windows windows or WiNdOWs here. Yeah macs exist and with the aid of some voodoo magic linux has been known to run but Windows is suported the best and will probably be the easiest option for a while to come.
Bear in mind that once you have the actual laptop you will need a mouse and probably a keyboard if you plan on doing office/graphics work at any length.
