I have set my system to use AHCI and it works great, but I wonder if there is possible to see the mode actually used from inside Windows and not only from BIOS? That is, how can I check this on other computers without a reboot and entering the BIOS setup.
Look at that screen shot you are using AHCI. One of those sata controllers provides two sata ports (0 and 1), one provides 6 ports (0 - 6) and the IDE controller which provides another 2 (0 and 1). I'm not using any ACHI on my computer, and all I have is the standard dual channel PCI IDE controller.