Upgrading Dell XPS 420 graphics card to Radeon HD 6850

Hey everyone! I know I posted a little over a month ago about upgrading my psu and my graphics card to 6770. I decided to switch to 6850 because I can get more bang for my buck. Anyway, I'm having a little problem with deciding on the regular sapphire or the sapphire vapor-x. Of course I know the vapor-x cools your computer better, but is it worth the extra 5 dollars and the 8 dollar shipping? The regular sapphire has free shipping along with a 20 dollar mail in rebate. There are no reviews on the vapor-x  so I'm a little hesitant to get it because the 6770 vapor-x had mixed reviews compared the amazing 6770 flex. On newegg there is no 6850 flex, just sapphire and sapphire vx . How do you guys feel about VX and just regular sapphire?

My dell xps 420 is still being upgraded from a 345w to a 650W Hx. I know that is going to work out with my computer and my new graphics card. The only problem is (once again) will this graphics card work? The other one was PCI-express 2.0 x 16 and this one is 2.1X 16. I'm pretty sure it will work because I believe 2.1 can work with 2.0 like 2.0 can work with 1.0, but then again I'm not really sure. Any other concerns I should worry about? Thanks guys!