Ok, I can't say fairer than that!

So, lets get to the business end ...
There are 3 possible reasons for the monitor to support 16bit over 32bit @ 1440x900;
1) The driver doesn't support it properly for some reason
2) The mobo is incapable of supporting the resolution at 32bit
3) The monitor was attempting to sync to a refresh rate outside of it's operating range
What do you refer to when you say the monitor acted like it didn't support it?
If it displayed a no sync/out of range message, then this is more than likely due to the refresh rate being above the threshold and not due to driver/mobo.
In reality, the only place you'd probably notice 16bit over 32bit would be during gaming, or watching movies/tv shows etc. I wont explain any further, this does it for me in a very simple way
Windows Display - infopackets.com. If you want a techy explanation (including RGB calculations), wikipedia is your friend
RGB color model - Wikipedia, the free encyclopedia. The specific section relating to 16/32bit is
here. As a reference, I came across a graphical comparison between 16/32bit while trawling the interweb for suitable articles to post here. You can view this file on imageshack
here.
With regards to the drivers from the Asus site, they are usually out of date. Personally, I think the Asus driver list for mobos is a good enough point of reference when hunting for newer drivers without digging out the manual, or consulting the device manager/belarc etc.
However, having said that, by far the best place for drivers, is direct with the manufacturer

.
As for the monitor, it appears MAG rely completely on DDC (Display Data Channel) for the la-*test*-('") TFT series monitors. This in effect has removed the need for drivers. In your case, if the monitor isn't picked up as the actual device instead of plug and play, there probably isn't much that it can be done.