I am fairly surprised by the vehement hatred for Nvidias video quality. I have the exact opposite reaction when I jumped to a 5850. I tweaked and tweaked and could never get a pic I liked. I finally gave up and just accepted.
I do understand the font thing though. I don't personally feel AMD was any better. However, once something bothers you it might as well big as big a difference as black and white. I get called out all the time because things bother me that most can't see or hear.
The 5450 is inferior to the newer cards in video, probably why you didn't like them, they just weren't as good as they should be.
http://www.tomshardware.com/reviews/radeon-hd-6450-caicos-blu-ray-3d,2920-10.html
For reference, a 7xxx card can score upwards of nearly 200:
http://www.kitguru.net/components/g...hd7870-royal-king-2gb-graphics-card-review/8/
I had a 6670 which does incredible video, and a 7770 and 7870 which look just like it. I think if you hit that level of hardware you'd be surprised.
I honestly tend to turn off everything but mosquito noise reduction, and set that at 20%. Make sure to turn off brighter whites, flesh tone correction, and everything else that reeks of unnatural post processing adjustment.
edit: noticed you said 5850. Dunno what the deal was there. I never had a 5xxx card. Differences between the 5450 and 5550 are apparent in that chart though.