Max resolution would be 1920x1080 per monitor, for up to 2 monitors. Motherboards don't support dual link dvi cables (there's no dedicated graphics card), so it won't be higher than that. There will probably be 3 outputs, vga, dvi and hdmi. Can't say for sure though, without knowing model of the motherboard.
For £6 more you could get a PC that would blow the preassembled one away:
*Better processor with unlocked multiplier, you could easily get to 4.3-4.4 GHz with it. It also has Intel HD 3000, better than Intel HD 2000.
*Faster memory, with 1600 MHz frequence, instead of 1333 MHz.
*Quality Corsair PSU. I bet the preassembled one contained cheap generic PSU.
However, if you don't need better PC but you want to save money, I could pick parts for it too.
For 500 Pounds is Too much man, if you would build a PC you'll win more. This time I used an AMD based system for better IGP (and less than 500 too! The IGP's much better than HD2000/HD3000 Of course!).
There are so many different ones out there..... my requirements are mainly processor ooomph and memory - the graphics are secondary, but must not interfere with the memory - so a discrete card is required.
I think you should invest some time to learn how to build the PC. It really looks way more complicated than it is. There are loads of youtube videos around, of how to build a pc, just take a look. You'll see that it's really simple! 6 months ago I built my first ever self built PC. I was actually afraid of it, but guess what, I got it done in 40 minutes. Just watch the videos, you'll understand.
P. S. The one your linked probably has a crappy power supply. It has weaker CPU and worse RAM.