What do you mean black bars? Ain't VGA also a severe limitation in regards to running 5040x1050?
In any event, see the stick at the top.
http://www.widescreengamingforum.com/forum/viewtopic.php?f=59&t=17827
It's pretty hard to explain but i'll try.
When i turn on 5040x1050 i get black borders around my desktop/game. It's like the monitor is out of sync.
But i'm unable to size the image of the monitor to Hor or Ver size.
When i do auto adjust it doesn't help.
From what i'm reading 5040x1050 is the max for VGA so that shouldn't be the problem right?
Also when i changed to Windows 7 64bit i had the same problem with 4320x900.
Switched back to Vista since i didn't get it fixed at all.
2 days later i read the topic you just linked and did it all on Vista.
Still no luck in 5040x1050.
I do not have a Camera or else i could take some pics.