SSD Upgrade

I have an ASUS CM 1630 Desktop.

I have upgraded the Vid Card to an Nvidia 550Ti
I have also upgraded to an AMD Phenom XII 945. I would have went with the 965 but lucky for me, I checked the compatibility on the mainboard, and it only supports up to 95w, so anything over the 945 is out.

Next upgrade is going to be a SSD.

M4A78LT-M only runs SATA 3Gb/s. So should I get the SATA II or SATA III versions of a SSD?

How much of a performance increase will i see? I keep reading that the SSD make load times virtually disappear for MMO's like Guild Wars. Will that be the case wtih this setup or no?

Any suggestions on a cheap one to get that would be a good fit for what i have currently.

This is the nearest PC hardware store
http://www.frys.com/search?cat=-69586&pType=pDisplay&&f... Internal

And this is a link to my mainboard.
http://www.asus.com/Motherboards/AMD_AM3/M4A78LTM/#spec...