No. I do mean the X1600's are more in the same league with the 6600's. The X1600 is more of a rehashed X700, which competes with the 6600. The X1600's aren't that impressive for a midrange card, especially considering the 6600GT can be had for just over $100 online, which is in the same price range as the 6600GT's---which also perform a bit better. This isn't to say you can't work with that kind of performance---I run a 6600GT myself and it's a great card---but ATi doesn't have a midrange card to compete with the 7600GT. The 7600GS is more or less the same performance level as a 6600GT from the benchmarks I've run across, but the 7600GT is the main midrange card from nVidia.
ATi's achilles heel in the past has been awful driver support, and for the most part, they've really come out of that crap--unless you're in Linux. What they need is a strong mid-range contender. True, the GeForce 7950GX is the fastest card on the market, but that's only because it's got 2 GPU's SLI'd together. ATi has the fastest single GPU on the market with the X1900XTX.