A 5850 lands pretty well out side of the price range set out and i two wouldn't recommend a 5670. If 100$ is really you'r Budget the fact that a 5770 cost about 15$ more then that at least and offers very little performance increase most likely doesn't make sense. But if you are willing to spend the extra cash mouse24 is right the 6670 is really the best you'r gonna do in the sub 100~ range though.
Well first off like i sad the 5770 is over his 100~ price range and for some people the price they list is the absolute most they can spend meaning the 5770 would be out of the picture totally. Also your not comparing the same cards i recommend the 6670 not the 5670 there isnt a big difference but the 6670 is a little faster i.g http://www.hwcompare.com/10870/radeon-hd-5670-vs-radeon...
Your also talking more power, and more heat with a 5670 then a 6670.
Again we would need more info from the poster because if he cant break 100$ then the 5770 really isn't a option.
EDIT: less power with 5670 about 2 watts lol.
Personally I would say the same thing but some times your budget is really tight and in reality that argument can go on forever if your gonna spend 15 bucks more for 30% more performance you could probably get 30% more for another 20 after that lol. I just felt that the 6670 was the best he could do for that price range a 5750 or gtx 440 is really a bad option in my mind.
Okay so to flintironstagg if again you look it seems his budget is at the most 100$ and I have not seen one 5770 in that range and for most people there max budget is pretty set in stone so it helpful to give advice using that price. Also AstroTC I think the 465 is a good pick to ,if you look at my post i actually recommended that exact same card from new egg but if you look its a recrt , some people aren't comfortable with that in fact as some one who uses there PC for many hours at a time and over clocks there GPU I wouldn't buy a GPU that wasn't brand new with a full warranty.
JJB I'm glad we are on the same page with that. A 90 day manufacture warranty is really not sufficient for a GPU you might be keeping upwards of 2-3 years. Technically if the card dies on day 91 you are out of luck and out of money,