I'd reccommend getting a DELL - thats what I use, its great, and everyone I know who has one is also happy with them.
Don't reccomend buying from a high street store such as pc world, dixons etc. WHy ? You are paying a premium and quite often the service is poor and staff un-knowledgeable.
Have a look at
www.dell.co.uk
I have a basic inspiron, which i bought back in april for under a grand and although slightly chunky is great.
One must - find out how long the battery will last !!!! Mobile chips usually allow the battery to last longer, having said this Dell's new smartpc is a desktop chip and the battery lasts just under 2 1/2 hours which aint bad, good value and having seen one in the blood looks nice too.