ext, we need to make sure our ATA/ATAPI ACHI controller is set to use trim.
EDIT! 3/22/10: The new INTEL chipset drivers 9.6.0.1014 support TRIM! Use these instead of the MS AHCI ones for Intel Chipsets.
RAID: Intel® Rapid Storage Technology Driver for Intel Desktop Boards
For non-intel chipsets:
To see/change it, go to device manager and select IDE ATA/ATAPI controllers. If it says "Standard AHCI 1.0 Serial ATA Controller", you are good to go. If not, double click it and select the driver tab. Click update driver. Select browse. Select let me pick. select Standard AHCI 1.0 Serial ATA Controller.