Also is it worth paying another £80 to get the "Factory" version with -

Mbox 2 Factory Bundle

For added creative processing options right out of the box, Digidesign presents the Mbox 2 Factory bundle — a complete Mbox 2 system plus a set of potent Digidesign and Bomb Factory plug-ins (a retail value of more than $1,050!) with an iLok USB Smart Key that has those plug-ins preauthorized. Mbox 2 Factory plug-ins include:
moogerfooger® Analog Delay
JOEMEEK® SC2™ Photo Optical Compressor
JOEMEEK VC5™ Meequalizer®
Cosmonaut Voice™
Digidesign® Maxim™

http://www.digidesign.com/compato/xp/mbox2/

The above link will help you.

Active monitors can be used on the MBox2 outputs.

m box2

overall the m box2 is a good little performer but do get the factory bundle with it, the pc your talking about should run it fine but if your thinking of running any large soft synths then i would up the memory by another gig,pro tools 7.1 is a joy to use we have just upgraded all our pro tools systems to 7.1 with no problems what so ever, the one thing i would say is if funds allow why not look at the 002 system which has even more possabiltys with its extra inputs and out outs hope you found this helpful

Thanks, just need to decide on which mic and monitors to get along with the M-Box.

mbox

monitors are a personal choice and also depending on budget the best thing you can do is go to a stockest and take a cd with you and get them to play it through them for you but remember just because a set of monitors sound good in a shop your room plays a important part of how they will sound when you get them home make sure if your getting nearfields to place them at around your ear level and keep them around 1.5 metres way from you when your working with them,also try and make sure the wave path has no obstructions as to avoid any forward reflections.