I have it narrowed down to these 2 HD3870s any opinions on wich is better ?

well just off hand i would say msi. have you looked at the new 4850/4870's?

The one to get would be the one with a better warranty.

I've had the diamond viper 3870 for about 6 months and it has been 100% stable and it plays cod4 , crysis , bioshock , coh's , doom3 on high settings clocked at 827/1166 , no problems , 3d mark 06 , 877/1251 scored 11163 4977/5458/2458 its been a pleasure to use it. I just bought a visiontech 4870 from tiger direct for $299.00 plus shipping and it will be here on july 9th , You should buy a 4870 but the 3870 has been great and I payed $164.00 and free shipping back then. also the fan idels at 30% 46c and gets in the upper 60,s at load and that's about 70% fan speed at the stock fan settings , its also been a very quiet card ! good luck on your choice and enjoy ! for about the same money I would get the 4870 and get more performance than 2 3870's