Although it is the latest xf86-video-mga-1.4.9 driver, 
Initialization of g200e pilot is insufficient?
The latest driver doesn't work in my environment. 

I think that I need to set displays depth as 16.
When using the following patches, xf86-video-mga-1.4.9 driver worked.

--- xf86-video-mga-1.4.9/src/mga_driver.c.orig	2008-07-31 11:28:05.000000000 +0900
+++ xf86-video-mga-1.4.9/src/mga_driver.c	2008-07-31 11:34:04.000000000 +0900
@@ -1632,7 +1632,7 @@ MGAPreInit(ScrnInfoPtr pScrn, int flags)
 {
     MGAPtr pMga;
     MessageType from;
-    int i;
+    int i, j;
     double real;
     int bytesPerPixel;
     ClockRangePtr clockRanges;
@@ -1899,9 +1899,13 @@ MGAPreInit(ScrnInfoPtr pScrn, int flags)
     if (pMga->SecondCrtc)
 	flags24 = Support32bppFb;
 
-    if (pMga->is_G200SE)
+    if (pMga->is_G200SE) {
 	pScrn->confScreen->defaultdepth = 16;
 
+	for (j = 0; j < pScrn->confScreen->numdisplays; j++)
+	    pScrn->confScreen->displays[j].depth = 16;
+    }
+
     if (!xf86SetDepthBpp(pScrn, 0, 0, 0, flags24)) {
 	return FALSE;
     } else {