playable; yes. but not at 1920x1200.
just grab a HD4850 (at the minimum, considering the powerhouse of the dual Xeons you're packing) and you'll be kiting rings around the best of them.
if you're set on getting the game anyway, i'd recommend pre-ordering now so you can play... ahem, test the beta as soon as you upgrade. if you've got a best of a computer like that, and you're looking at upgrading then what's a mere $45?