but it does need the 300w powersupply, so your 250 will not cut it. Newegg.com has some 300w for about $20, but i'd recomend just bumping up to atleast 550 watts.
yep the game engine is the same. There has probably been a little tweaking, but it's still the same engine. And I'd invest in a good psu, it's not just about the wattage. Right now I have a cheap psu and the voltages are definitely not stable.