Beyond3D has now posted a preview of the GF FX 5600 Ultra, which you can see here:
http://www.beyond3d.com/previews/nvi.../index.php?p=1
It's compared to a GF4 Ti 4200, and the result is quite disappointing, as the 5600 Ultra loses out to it in most benchmarks

Just take a look at Max Payne and UT 2003, for example:
However, it has improved AA and Aniso which doesn't cost as much performance. All in all, this reminds me very much of the Radeon 8500, which compares quite similarly to the Ti 4200 and also has better AA and Aniso. The similarities are quite striking here, so I found myself thinking, "What? Did they buy up some 8500s from ATI and relabel it as FX 5600 Ultra?"