I've bought stuff from Dabs, novatech and simply all before and they are good firms.
If I were buying a laptop I would pay the extra for a HP or an IBM thinkpad and definetely stear clear of compaq (they are very good machines but all the proprietry stuff is v annoying). Many companies buy these in bulk. Thosiba make robust stuff.
I recently bought a second hand thinkpad, becuase its a massive seller so I find spares - batteries etc very easy to find. Also IBM's website is v.comprehensive e.g I've downloaded the complete user manual and specs for my machine. I can recommend
formatting link
for second hand ones - I got a thinkpad 600, 266hz, 128MB, 4G for £145 this is perfect for surfing on the sofa wouldn't use it for work - far too slow. The hard disk failed they sent a courier out to pick it up and they replaced it with a 10G one. Why buy on ebay from an individual for a similar price?
Also remember when specing out a machine - that unless you do loads of graphic stuff, number crunching high end gaming you rarely max out the processor. So compromise get a lower speed proc and more - fast memory and a bigger and faster HD. Having more memory and if possible 2 HDs (one for windows swap file the other for data/programs) which are fast speeds up normal applications more than a faster processor would.
Also make sure it has the latest bus technology you are interested in e.g. the latest hardware version of USB or firewire.