Radeon 6850 vs 5830

6850 is a lot better option.

The HD 6850 would be better as it is the more modern card of the two.

Get the 6850.

6850>5830

5850>6850

if you play games get 6850, if you don't and just need gpu for your reasons get lesser one,

I just need it for video editing. I won't be doing any hardcore gaming

then get 6850 it's good for both.

Video editing is more CPU dependant than anything, particularily for transcoding.

I don't see the need for you to spend more.

6850 <£100 http://www.aria.co.uk/SuperSpecials/Other+products/XFX+...
Limited time only

I will get the 6850 if i were you  

I say go for the 5830 - it's 33% cheaper, but the 6850 is only about 20% better. If you're not going to play many intensive or modern games, grab the cheaper option. Though I suspect you'll get more into PC gaming down the road with either of these cards.