Thanks to all for your responses.
The problem with the monitor is that I don't really have much room for a screen bigger than say 23" so I'm a bit limited in that regard, I'd almost prefer a 21" or 22" as I'll be sitting quite close to the monitor. I went for the Benq as it's 1080P and it's a LED LCD - which should give a better contrast ratio. Would I be just as impressed with a CCFL LCD? That Samsung monitor you linked looks good Mr. May, I presume you think that's a better choice than the Benq?
Also, the general consensus over in the graphics card section is that it's not worth the extra £100 for the 5870 over the 5850 as you can OC the 5850 to 5870 performance. I know the 5870 can OC too but it's not a performance increase worth it relative to the extra price.
I can stretch to £1,800 if necessary but not really past that.