I've recently started building entire page formats within a graphics editor and making the basic background and fixed elements into a single .JPG or .PNG file for use as a background. It reduces the overall number of files in your uploaded VSD folder by a staggering amount and as far as I can tell doesn't affect users pageload times in any way. This also gives you consistent and seamless page transitions.
It sounds like that's what you're after. I design the basic page using VSD and when I reach the final draft I condense/reconstruct as much of the graphics as will be necessary for each page into a single image using a graphics editor and assign that as my background image. I usually have two to three similar backgrounds with minor changes within the page elements to accommodate a "variety" of pages that utilize differing active flash components.
I'd suggest using Paint.NET, it's FREE and has very sophisticated graphics capabilities. I won't say the learning curve is EASY because the help files can be a little vague as it's the product of a programming class and has been developed by largely student contribution I think. The help dialogue is not flawed but also not written by a technical writer/editor so I think in many cases the dialogue assumes you have prior knowledge of other working elements within the applications processes which in my case means they're explaining something outside my level of competence.
Redmond, OR - the High Desert