They say use the green slots first because the green slot is channel A so it's first in the lineup. However this mainly applies to running a single channel Setup, OR if you aren't running dual channel, OR if you have lesser than PC3200 RAM I suppose. Other than that you'll want to put one stick in the green and one in the purple to obtain Dual Channel Mode.
As long as you use two chips that are the same and put them both in a green slot it will work in dual channel mode.
This is incorrect. You want one stick in the green slot and one in the purple for your RAM to run in Dual Channel mode on that motherboard.
Putting both sticks in the green slot will get you SINGLE CHANNEL, which you'd rather have dual channel anywhere.
All it's saying is for better stability and assurance you want the first stick to go in green slot because that's the first in the lineup. If you want single channel throw the other stick in the green at the expense of having it run at 333 if it's double sided. Otherwise put it in the purple.
How about the Abit 3rd Eye? Always thought of it better than that MSI.
Either board is good, both offer good quality, stability, and quite a bit of options in the BIOS. Each have a couple things the other doesn't however. MSI has 8 channel audio while ABit has 6 channel Audio onboard. MSI has dual onboard LAN, whereas ABit I believe only has one (not that you need two). They both feature a program that allows for some OC'ing and system monitoring. uGuru for ABit and CoreCenter for MSI. uGuru is more indeptth and thorough than corecenter when it comes to the mild Overclocking options and overall I say uGuru is better but corecenter performs it's needed duties
DOUBLE EDIT: To elaborate further BTW....if you look at MSIs homepage they show you what combinations will cause the memory to run slower than normal. It'd require you putting two double sided memory modules in the same channel. Meaning if you put two sticks of PC3200 in both green slots, then yes it will only run at 333MHz...
BUT you don't want to do that anyway. If you got two sticks you will want to put one in the green and one right next to it in the purple. This will give you Dual Channel, and will retain it's 400MHz FSB with the double sided memory modules
look at the chart at the very bottom and it says what a single and double memory module combination does as far as speed goes.