I've found an answer in Intel's SSD Toolbox User Guide:
If your computer uses Microsoft* Windows* 7 and the standard Microsoft AHCI driver (the default setup for normal configurations without RAID), the Intel SSD Optimizer works; however, you do not need to use the Intel SSD Optimizer because Windows 7 implements the Trim functionality natively.
If your computer uses Windows 7 and Intel Matrix Storage Manager version 8.x or Intel Rapid Storage Technology driver version 9.5 or earlier (which can be used in place of the Microsoft AHCI driver), Trim functionality is not implemented, and Intel SSD Optimizer is required to enable Trim.
Intel Rapid Storage Technology driver version 9.6 supports the Windows 7 Trim command, but for non-RAID configurations only. In these configurations, Intel SSD Optimizer is not required to enable Trim.
So for me, since I don't need RAID, it's either MS-AHCI or Intel-RST 9.6 or newer.
I'll give the RST a try...