I know what you mean about knowing a particular res will work via another OS on the same box and having to figure out how to make it work in another one. It's just a good idea to encourage getting *exact* brand and model specs right from the manufacturer to avoid any problems. Since my last post I've done a buncha research on xorg.conf and setting resolutions and I've learned a few things.
First off, "DPMS" is a power saving protocol that accomplishes such things as screen blanking assuming you have a kernel w/ APM and/or ACPI enabled. It should not be responsible for getting a particular resolution wheras EDID might. You might wanna look at "read-edid" here http://freshmeat.net/projects/read-edid. You may also notice in the nVidia ReadMe that it mentions the "EDID" opton along with several other neat configuration possibilities like "Digital Vibrance".
Anyway the simplest way to get 1024x768 is to list it, and it only, in the "Mode" option in the "Screen Sections" of xorg.conf. Assuming you have your sync rates listed correctly and/or "edid" enabled, you will get that resolution. Listing multiple modes is certainly possible but I'd recommend listing the most desirable first. For one thing AFAIK this establishes screen size and all other modes will be given that screen size resulting in a virtual desktop ie one that is larger than the screen.
If you want to gain some more control I suggest you become familiar w/ "xrandr" and "xvidtune". If you aren't up to command line interface, newer KDE has a "Display" section in "Control Center" which allows the setting of resolution and refresh rates. However it takes it's cue from xorg.conf so won't allow anything it sees as beyond the range of ability so it is still important to have the correct sync rates in xorg.conf.
BTW I just noticed that someone else has nVidia and you apparently have a Matrox card so some of the above specifics like "DigitalVibrance" doesn't apply to you but "read-edid" should still function for you and help you write a proper xorg.conf enabling or disabling EDID, whichever works best for you.
Incidentally for everyone that doesn't yet know, you can avoid too many needless hits in google by using "www.google.com/linux" which limits hits to linux related ones.
Hope this helps
This is the xorg.conf file in FC2. The only thing that's different is the depth. In Slack, I had 24 but this 16.Code:Section "Device" Identifier "Videocard0" Driver "mga" VendorName "Videocard vendor" BoardName "Matrox Millennium" EndSection Section "Screen" Identifier "Screen0" Device "Videocard0" Monitor "Monitor0" DefaultDepth 16 SubSection "Display" Viewport 0 0 Depth 16 Modes "1024x768" "800x600" "640x480" EndSubSection EndSection Section "DRI" Group 0 Mode 0666 EndSection