Here the 06 numbers look very close.
8600GTS
======
E6600
250gb 16mb cache Sata 3gb/sec
2gb 6400 Gskill ram
HDR Tests
1 - Canyon Flight (SM 3.0) 18.063 FPS
2 - Deep Freeze (SM 3.0) 22.653 FPS
The "leaked" HD2600XT
=================
Radeon HD2600XT(3DMark06 and game benchmark)
Computer hardware configuration:[display card:RV630]CPU[Core 2 Duo E6600]
HDR Tests
1 - Canyon Flight (SM 3.0) 18.299 FPS
2 - Deep Freeze (SM 3.0) 23.799 FPS
They look very similar in 3DMark06 but we all know the 8600GTS tanks in games compared to it's 06 marks.