Or you can assign the affinity timing of the sound system to CPU-1. If Windows is set up correctly and the dual core hotfix applied right, it will always boot any 3D application using only CPU-0, which is the correct way to run games smoothly in WindowsXP on dual core processors. Windows VISTA will however be different.
By assigning CPU-1 affinity to all audio processes (or any other program being run with FS9 or FSX) FSX or FS9 will never see a single hickup from any audio bus time or process and you can take full advantage of a dual core processor with games.
Most people asume because a game is not multi-thread, running a dual system is a waste... far from it

Mainboard: Asus P5K-Premium, CPU=Intel E6850 @ x8x450fsb 3.6ghz, RAM: 4gb PC8500 Team Dark, Video: NV8800GT, HDD: 2x1Tb Samsung F3 RAID-0 + 1Tb F3, PSU: Antec 550 Basiq, OS: Win7x64, Display: 24&

