Any one of the Core 2 products will be faster then the D925. If you can get a Q6600(BIOS 1612 required) you will be very happy with the speed increase. Plus you will have 4 cores. If you do not want to spend $200 get any of the Core 2 Duo E6600, E6700, E6420.
The newer E6850 is 1333 FBS that will not work
Supported CUP list from intel for that boardhttp://processormatch.intel.com/CompDB/SearchResult.aspx?Boardname=dp965lt
Please note some of the older Core 2 Duos will be harder to find, But will be easy to find used.
Photoshop will use all the cores. You will see a huge increase in filter and changing masks.