AHCI and SSDs help

[goatmonkey]

So I caved in after the recent RPS article and got an SSD. Thinking it is basically just a faster HDD I got it set up and installed Windows on it and everything works perfectly fine and it is very nice and fast.

Then today I got to the point where I started actually reading about how to set one up properly and I came across AHCI and the fact I should have set my BIOS to use it before I installed Windows.

There are two settings related to AHCI in my BIOS I can see (SATA RAID/AHCI) MODE (currently set to nothing) and ONBOARD SATA/IDE CONTROL DEVICE (currently on IDE)

My questions are: is using AHCI really going to dramatically increase performance/are there any downsides to using it? would I need to change both the previously mentioned settings to AHCI or just RAID/AHCI Mode before reinstalling Windows?

I barely understand what AHCI is (in fact I don't at all) and Google is only confusing me further, so any links to quality articles on the subject would be much appreciated.