Did a weekend beta test and it played wonderfully on my pc, yet my pc shows that it does not meet the minimum requirements. I have an Intel Pent E2220 2.4, 8gigs ddr2 and a 9800 gt 512. Ran like a dream on my pc even with firefox open for several hours.
My old pc, (yes this is my newer one) I had a 300W power supply, it was barely able to run my P4 4 gigs with a 9500 video card. When it eventually went out because it wore itself down it took my graphics card with it. I am kinda surprised 300W is powering your system.