🚀 go-pugleaf

Hi,
  I'll be buying a 22" Mitsubishi Diamond Pro 
http://www.necmitsubishi.com/products/home/ProductDetail.cfm?product_i
d=232&division=MITSUBISHI and am now looking a various cards to drive 
this monstrosity. Mitsubishi specs say it can go to 2048 x 1536 @  86 
and my job now is to match it to a card provide the signal. Although I 
will probably have the screen set to 2048 x 1536 I figure if the card 
can do this it will be able to provide viewing at lower resolutions 
flicker free.
  My needs are to provide clean displays of various large data sets in 
2D, sometimes rotate them in 3D and a little low-tech gaming like Age 
of Empires, Sim City. I'm a little confused because cards advertised 
with 64 MB, 128 MB, or now 256 MB of memory all claim to be able to 
display at resolutions near to my 2048 x 1536 benchmark so there must 
be more than aggregate memory that determines ability to run large 
monitors at high resolutions.
  The Matrox P750 seems to a reliable choice for the job but lacks 
some of the fun stuff of say the ATI AIW 9000 Pro or GeForce4 Ti 4600.
Will $150-$200 get me a reliable, flicker free card that can display 
at high resolutions (that way I can see more of the data set) or am I 
asking too much of a card in this price range?
One last question. What is the end result of setting the screen to a 
resolution and refresh rate that the card doesn't list? For example, 
the monitor mentioned above lists a capability to display 1800 x 1440 
@ 92 Hz but the closest a Radeon 9800 Pro comes in terms of its spec 
sheet is 1920x1080 @ 120. How would this display on the screen?
Thanks for the help with these questions.