do I need to install the Intel Matrix Storage Manager + drivers on the above when using AHCI in the bios to get trim working or not?
This is a new build and I am a bit confused as regards to IMSM drivers. I am pretty sure I do not need them and just install Windows 7 as per normal after enabling AHCI in the bios (Asus board that has AHCI enabled, not the H55 Intel board without AHCI)
I found the Intel New Users' Guide very helpful. I'd sugest you read it. It was something I stumbled upon on the website but it provides useful guidance. I installed the Matrix Storage Manager as suggested by this Intel guide and it was useful as it lets you know the appropriate drivers are installed and whether NCQ is enabled on all your drives. I also found out the Superfetch service should be disabled so the guide is well worth reading.