Ok thanks to the help provided on page 1 of this thread I've been able to get my overscan issues sorted
The text is a little harder to read now prob due to the scaling but heres what I did to get this working nicely on 720P
mind u this is after I've done a loopback install
right click / go to window manager and then click exit
in console type su to get root, entered xbox as password
then typed fbset to get my settings
and followed the instructions by subtracting from resolution and adding to margins until I got it nice.
at any time I clicked startx to reload x and see where i ended up, exiting it again back to prompt
When you have it right take note of yoru settings
go to breeze and then open the linuxbooter.cfg or whatever its called in the /opt directory and add that item into the script (note you need to still have root to do this)
and woola,
my settings for 720P on a panasonic PV500A 42 inch HD plasma are
fbset -g 1216 688 1216 688 16 -t 13468 252 102 36 21 80 5
as i said its not quite perfect but a lot better than so much info being offscreen, though text in mozilla is now quite hard to read properly

(any ideas on this?)
You are sooooo awesome. You just answered all of my questions, and got me a perfect setting on the second try. I ended up taking yours and taking 8 off of the height/width and adding it to the left and upper margins. Now it's prefect.
Before I didn't know that you had to close x to get the settings to change correctly, I also had no idea that you had to be super-user to get write priveliges to bootlocal.sh. So I was having a problem with that as well.