Fx6100 with 6670 or 6850

Hello, i recently bought an hp with an fx 6100 with 6670 1gb gdr3 card. Its already being shipped it was 718 total with tax/shipping.

To my dismay today i saw an fx 6100 at amazon with a 6850 for 819$ a cyberpower. should I return this hp? Also im using it for video editing mostly not really gaming. Will this upgrade be worth it? I'm a little tight on money but will the 6850 make a difference for hd video editing. I suffer from "return guilt" and hate returning but I feel its the right thing to do! Also the HP case might be too small to ever upgrade the video card and it only has one pci x 16 port not the 2 needed for crossfire

The HD 6850 is roughly twice as powerful as the HD 6670, so it's a no brainer really. Also makes for a good long term option.