product display on home page?

What's controlling the layout of the products on the home page? It's two columns with lots of hortizontal and vertical whitespace and I want to make it three columns and tighten up the white space. How do I do that? Thanks!

modules/HomePageProducts.ascx     RepeatColumns="3"

i think product.css  is where you need to start with the 'tightening'

That was exactly what I did. thanks!