I wanted to buy a new SSD but then I found out that AHCI support in the motherboard is important. I looked into Google and couldn't find out if my Intel DG41TY motherboard support AHCI. The manual doesn't mention it but maybe the newest BIOS has it.
From what I can tell it doesn't support AHCI. However, this isn't such a big deal (as in "can't use SSDs").
SSD drives will work just fine in classic SATA/IDE mode. Some vendor provided tools might not work (in my case those provided by Samsung), but the drive will still work and the built-in firmware will still be able to alleviate wear caused by repeated writes (plus you'll still get a speed increase, even on SATA2). Also the operating system most likely will be able to use features such as the TRIM command (given it's supported, e.g. Windows 7 or Windows 8 but not Windows XP or Windows Vista), you'll just have to make sure to use the proper drivers (and, based on your mainboard/controller, not run in RAID mode; sometimes TRIM won't work then).
Just make sure you're leaving some free space (unformatted; not assigned to any partition). Once you get a new motherboard later on you can still switch to AHCI.
It seems that the latest BIOS update for that mobo is version 0045 and I checked its release note here: http://downloadmirror.intel.com/19202/eng/TY_0045_ReleaseNotes.pdf
This document has all the history of previous versions as well but unfortunately it did not mention anything about AHCI options, which means you can't turn on AHCI.
I am not sure if its chipset actually supports AHCI but just BIOS did not give you the option to turn that on. If this is the case, then there's still a (very faint) chance to force it to run in AHCI mode using external tools such as GRUB, but it may be waste of your time as only a few models of machines such as old Mac book pro and Vaio notebooks got the trick succeeded. If you're willing to use linux, things will get little bit easier but the chipset itself should support AHCI anyway. It's a complex issue and usually it's reasonable to think that, at least on Windows, no BIOS support means no AHCI at all.
Anyway, it's an old issue and probably you've upgraded your mobo already. If not and you still want to use AHCI on Windows with the environment you had, the last resort will be buying an external AHCI adaptor which may not be reasonable as it makes you spend money for the old hardware. It is true that turning on AHCI will give you not only "SSD trim" but also performance advantages, but it may not worth spending more money.