I'm not at my 7 box but it's a configuration option on the individual sata port. So find the sata controllers in the hardware manager, then there should be 2 sata ports per controller and then on the sata port properties there should be the check box. Uncheck it only for the one port your SSD is connected too, rotating drives still need it for best performance (It's why it was invented).
Sry I still cant seem to find it... ive looked under Hard Drives and IDE ATA/ATAPI contollers 
My Computer
At a glance
Windows 7 x64 Ultimatei7 920 2.66Ghz Overclocked to 3.40GHzCorsair XMS3 6GB DDR3 PC3-12800C9ATI HD 4870x2
- OS
- Windows 7 x64 Ultimate
- CPU
- i7 920 2.66Ghz Overclocked to 3.40GHz
- Motherboard
- Gigabyte EX58-UD3R Intel X58
- Memory
- Corsair XMS3 6GB DDR3 PC3-12800C9
- Graphics Card(s)
- ATI HD 4870x2
- Hard Drives
- 1 x SSD 60GB
1 x Western Digital 1TB
- PSU
- Corsair TX 650W
- Case
- Antec 902