I have not seen any specific
OC reports for that board, though it should do pretty well since it's from DFI
The
ram you chose should also do well, most DDR2 667 will run at DDR2 800 speeds with a slight bump in voltage.
It should be about double the performance of you current Sempron in 3DMARK 06 and Quake 4 (Both show massive improvements with Dual Core
CPU's and the larger cache size.
There are reports of the 3800+ AM-2 running at 3GHZ with high end air cooling, so you should be able to reach 2.6GHZ or more with out much trouble at all