I downloaded your image and checked it out in photoshop and can’t see a problem with it.
I also have an old laptop with a partitioned hd and I run Ubuntu 8.04 on one half of that. I just checked out your page on that in Firefox (3.0.1) and there is no line showing around the image. Could it be a problem with your monitor? I’ve had a hell of a game trying to find compatible drivers for the nvidia graphics card on the laptop, that’s why I’m still on 8.04, upgrading leaves me with a black screen.
Anybody else with Ubuntu want to take a quick peek? Lines or no lines?
Is it possible you have a background color set to black(or some other dark color) and a left-margin of 1 and top-margin of 1 while your width is an absolute size? Meaning you have a absolute width of say 60px but since your image has a left-margin of 1 and a top margin of 1 with a black background it’s being bumped to the right and down by a pixel simulating the one pixel left and top borders?
I hope I didn’t confuse more with my horrible attempt at a description.