If I recall correctly, the original expectation for DX10 in FSX was for a substantial increase in performance (read: frame rates). Somewhere I got the explanation that DX10 would take better advantage of the power of the latest GPU's. So far, I haven't seen a performance advantage to DX10, but I realize that it is just a preview and that the drivers (nvidia in my case) are not fully tuned. But eventually will we get better frames from DX10, or is that no longer a realistic expectation?

I would just say to get used to what you have. With no further updates to the core of FSX, DX10 at this point will not be a miracle.

Actually, with driver advances, I expect DX10 performance to increase in the next 6 months.Early reports of the latest nVidia driver seem positive in the performance category...RhettAMD 3700+ (@2585 mhz), eVGA 7800GT 256 (Guru3D 93.71), ASUS A8N-E, PC Power 510 SLI, 2gb Corsair XMS 3-3-3-8 (1T), WD 150 gig 10000rpm Raptor, WD 250gig 7200rpm SATA2, Seagate 120gb 5400 rpm external HD, CoolerMaster Praetorian