Trouble with xorg.conf on BT5R1 in VirtalBox

[mjl3434]

I am trying to get my VirtalBox install of BT5R1 to run at 1680x1050. I have the guest additions installed, and have had previous success with this resolution under Fedora. I noticed that there is an xorg.conf file in /usr/share/xresprobe/xorg.conf, however I'm not sure if it is being used because the xorg log file (/var/log/Xorg.0.log) shows "(==) Using config directory: "/usr/lib/X11/xorg.conf.d" and I don't see *any* references to the /usr/share/xresprobe/xorg.conf file. I started X using "startx".

Can someone give me a brief explanation of how X & xorg.conf work under BackTrack 5?

What do I need to do to enable the higher resolutions like 1680x1050? (Editing the xorg.conf listed above did not work)

Anyway my goal is just to get 1680x1050 working within the VirtalBox install, so any instructions that would point me in the right direction is appreciated. Currently I'm not sure if I'm even headed in the right direction.

[mjl3434]

It looks like my guest additions were not updated, after update everything is magically working. I'd still love to understand what is going on however, if someone can help.