Both processors were tested on the following test system:
Here are the results:
ATI RD790 based motherboard GeForce 8600 GTS Corsair DDR2-1066 2x 1GB
We're not sure how credible these benchmark results are but it looks like the new quad-core Phenom X4 gets beaten by the old dual-core Athlon 64 X2 6400+ in most benchmarks. The X2 6400+ is clocked a lot higher but AFAIK AMD's quad-core Phenom processors won't reach significantly higher clockspeeds this year.
The Phenom X4 GP-7000 will be launched later this year . This quad-core CPU uses the AM2+ socket and has 4x 512KB L2 cache memory, 2MB L3 cache, HT 3.0 support and a 89W TDP. We're not exactly sure if this chip will be launched at 2GHz, most roadmaps indicate it will be either 2GHz or 2.2GHz. It's expected that this chip will be launched together with the GP-7100 which will be about 200MHz faster.