No, AMD's best APU is at 5570 level, while the 8800GT is at 5670 level. (And the top 8800 GTX was ~20% faster than the 8800GT IIRC). Intel is even further back.
2 years ago was Sandy Bridge. I wouldn't call the i5 2500k or i7 2600k "merely good." For top of the line, GTX 590 and 6990 were two years ago as well. "Merely good" compared to a 7970 GHz edition?
http://www.anandtech.com/bench/Product/618?vs=516
Nehalem dropped 4 and a half years ago. I don't think an i7 920 is going to be "nearly unsuable." 4870x2 was 4.5 years ago as well, and that's at the level of 5870/6950/7850. 4890 CF would fare even better.
A 920 and single 4890 would be faster than what I have, and my X4 945 and 6770 are perfectly usable.