AMD 7750 HD = $95 on Amazon right now
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I LOVE mine! I didn't exactly have the latest-gratest desktop so I didn't want to throw a $400 gfx card in there. Did a stupid amount of research. Basically this card is in the top 10 for Tom's Hardware graphics card hierarchy. To move up several brackets in that hierarchy you're talking hundreds more dollars.
The 7770 would still be a great choice but you're paying a little more to get up to that next bracket; 8th in the top 10. Where as the 7750 is 9th in the top 10. Is it worth it? Only if you have the base hardware to drive that card (CPU, Motherboard, buses, bridge, etc. etc.) In this case I honestly wouldn't consider money... it's like $20 were talking here... but do you have the base system to drive that card? That's what you gotta evaluate here.
I've ran aaallll kinds of cards over the decades. I prefer nVidia GPUs just as I prefer Intel CPUs. Yeah I've ran ATIs, AMDs, and everything in-between so it's not just brand loyalty. The nVidias just out-perform (usually) the ATI's competition cards. The Intels just outperform (and last longer in my experience) than the AMD's competition CPUs.
What I'm getting at is it takes a lot for me to recommend an ATI / AMD card as I prefer nVidia =) If money is not an issue; I'd go nVidia and Intel every time. However I'm cheap... so I often end up compromising.