wine users - Mar 2011 - Playing at custom resolution

I've got a display with a native resolution of 1920x1080. However, I usually
play games at 1280x720 because I often like to create screencasts of the games I
play (and my PC is not fast enough for capturing 1920x1080).

Now I noticed that wine does not provide the resolution I want, which means that
this resolution does never appear in any game. If I set the resolution with
commandline parameters (e.g. in games like CSS or Bioshock), the games always
change the resolution to 1280x1024 automatically at startup.

However, if I enable the virtual wine desktop at 1280x720, all games provide
this resolution. The problem is, that I want to play in fullscreen mode instead
of in a window which is not as big as my display. So here are my questions:

-Is it possible to go into fullscreen mode with the wine virtual desktop?
-Can I add resolutions to any wine config so all games will provide the custom
resolution of 1280x720 as a native resolution?

Thanks in advance!

Have you tried setting the resolution with xrandr first?

Thanks for the hint, but I get the following message:

"Size 1280x720 not found in available modes"

However, I know that this resolution is possible since other native games like
"Penumbra" support it.