The problem is not a conflict with DirectX 9.0 and DirectX 10.. Vista has both built in..
the problem is that Orion Pirates was built off Empires at War which is DirectX 7.. updated to DirectX 8 in Orion Pirates.. and Vista has all DirectX versions prior to DirectX 9 stripped out.
XP has support for DirectX 6 to DirectX 9 .. but has no support for DirectX 10
as such, XP can work DirectX coding as old as DirectX 6 properly with little or no compatibility settings.. as such, since Orion Pirates is DirectX 8.0a, XP can handle the coding just fine where Vista only has DirectX 9 and DirectX 10 .. as such, it has to Emulate DirectX 8 and older, and with Orion Pirates, it emulates DirectPlay for DirectX 8.0a poorly with the game code thus causing some connectivity / interaction issues that we are trying to resolve if at all possible..
The problem is that the game is coded in DirectX 8.0a and Vista is not designed to support programs that old.
Now some things have improved connectivity and logging in.. however there are still problems during server updates of the game map, news generation, repairing / purchasing ships...
Now drafting and mission play works just fine, but returning to the server with the character and map updating makes for a game breaker as it takes up to 2 min to move from the hex..
As I have been recommending, Dual boot your system with both Vista and XP.. this way you can still enjoy the many benefits that Vista offers and you can still load into XP for older games like Orion Pirates.
For Dual Boot.. you can check my posting in the Engineering section or contact me by PM.