Dell do some really good monitors for the price, theres one that was reviewed in 3d world a while back that got rave reviews accross the board, it was the 2407WFP, it had a low viewing angle compared but it was something like £150 cheaper than the nearest rival.

I run my laptop at 1900 X 1200 and its great, lots of room to work, but I would just make sure that your graphics card can go up to that level.