[beyondinferno]

Okay, I've been working on this for about a full 24 hours now and am getting nowhere fast.
I've got an athlon x2 and asus hd3450 and am trying to run XBMC live (Dharma or Camelot) and either it wont boot to xbmc at all (no 3d drivers found) or it has huge black borders (underscan) and no audio through HDMI. I've tried using the ATI proprietary drivers and radeonhd on both live versions (I'm installing to a HD by the way), and I can't get anything working correctly. If I install Ubuntu 10.04.1 i386 everything works out of the box. I am now trying to install XBMC from svn in Ubuntu using RadeonHD and if that doesn't work I'm gonna try ATI's drivers. If I can get it working that way, is it possible to disable gnome and have it boot to xbmc after the setup is completed? If not, does anyone have a walkthrough showing how to get Live working with this card?
Any and all help is really appreciated.
I'm still a pretty big n00b with linux by the way, so sorry if this is a simple fix.

Update:
I got everything working with Ubuntu 10.04.1 and the latest SVN, but performance was pretty bad (menus were a bit clunky and 1080p would drop to ~10fps for 5 mins or so before running well for 5), so now I'm back to trying to get Live Dharma beta 3 running. I can't get radeonhd or catalyst running at this point (I think due to xorg.conf issues) but the level of support (and my working knowledge) is dismal. If anyone has any ideas on where to go from here, I'm all ears.

[beyondinferno]

So, I got everything working in lucid but still have an underscan issue... I've found like 20 threads complaining about it but not one lists a solution (please don't tell me to use an nvidia card). Any ideas?

[divingmule]

If your using ATI's proprietary drivers, open catalyst controll center and look for "scaling options" I think it's called.

[beyondinferno]

There isn't that option on the version of catalyst that I'm running.
I've figured out what commands to use to fix it.

Code:

sudo aticonfig --set-dispattrib=dfp2,sizeY:700
sudo aticonfig --set-dispattrib=dfp2,sizeX:1239
sudo aticonfig --set-dispattrib=dfp2,positionY:10
sudo aticonfig --set-dispattrib=dfp2,positionX:22

and that's running through HDMI to my Panasonic 42" 720p TV
The only problem now is these settings wont survive a reboot. Any way to script these to run at startup, or better yet, to have them just save?

[beyondinferno]

If anyone has a 3450 with the RadeonHD drivers (open source), could you post your working xorg.conf? I have most of the settings I need but I'm missing a few.