Hi Jenn!
I took a look at your site and it looks very nice. Do you know why you aren't making money with it? I would say your first step is to figure out what went "wrong" with the first site and see if it can be fixed before repeating the mistake with a second site.
Before building your textures site, did you run the numbers and see if the demand was there? How about the supply? Was it too saturated a niche to break into or too narrow to really draw enough traffic?
My next questions are how many pages do you have built on that site? Are you getting steady traffic?
You mentioned that this site is for things like scrap booking, greeting cards, etc., but you don't seem to have made use of those keywords and related phrases. Why don't you use the brainstormer to find good keywords relating to those topics and build pages for each one? That will bring in more targeted traffic and that site will begin to pay. I hate to see you lose all the work on such a nice site.
If you are considering building another site, the only way you can really determine if it is going to be a profitable niche is to run the numbers and do the research. Since you have an SBI site already, use their brainstormer and MKL to do a search on myspace graphics. See what the numbers tell you. Their brainstorming tool alone is well worth the price of SBI all by itself.
Holly's book is good for beginners, but it isn't going to provide you with more than what you have already available to you. It is more about the different ways to earn an online income, niche sites being one of them. But it doesn't have the tools and step by step guide that you already have in SBI.
It's my understanding that when you purchase a site that Holly sets up for you, it is more or less the shell. You are still going to have to do all the research and building yourself. There is no way she could possibly do that for everyone.

Of course, it is up to you how you spend your time, but I see so much potential in the site you have already begun. There are so many ways you can expand on that if you just use the tools you've got to find the keywords that you can adapt to your concept.
Hang in there.