Xorg custom configuration to not use a given area

[Carlos Baiget]

hello all,

I've changed the lcd screen of my eeepc which is 1024x600.
The problem is, the replacement is not exactly the one i needed and 
although it fits well, i cannot see the top first 5 or 6 pixel lines, 
because they are hidden behind the screen bezel.
My question is: could i trick Xorg to work as if the display were, say 
1024x590 and ignore those lines? I prefer to lose them than having gnome 
panel cut in a half.
I'm using ubuntu 10.04, with xrandr v1.3

I hope i've explained myself well...

Thanks for your reply.