that's a decent spec computer and I've always liked mesh, they do make decent stuff, it is almost identical specs to one I purchased for work earlier in the week which I got for �595 (ex vat) so in my opinion the pricing is about right on it too.
As VHG says though, at this time I would either wait for windows7 or at least double check that you do get a free upgrade to it from mesh before buying it. Keep in mind that if you go for the free upgrade route you may well have to wipe the system totally and install everything again.