Well, you can do that, but you have to realize that in some cases, but it depends on what you're priority is in your computer. You need to work on some key decisions like whether you want SLI or not, whether you're going SATA or still working with IDE and what socket CPU you're going for, from then, you can work within those categories to find what you're looking for. Sometimes it's hard to find the exact mobo if you select everything else than look for one.
I was only suggesting to start from the mobo so you can decide the basics of what you're looking for, and then go from there, but you can do it either way.
I actually built my computer by looking at a CPU, looking at a decent mobo, and then looking at what I needed and norrow the mobo down, then went from there. (I knew I wanted PCIE and something with both SATA and IDE connections, no SLI because I was on a budget, and no pricey ones, for the same reason). I still find it funny that my RAM was more expensive than both my mobo and my CPU, lol.
