If you take a quick look around some of the case modding sites, you will find lots of suggestions and guides on painting your case. I've done 2 cases now, and I don't think the brand of paint you choose makes a major difference. Obviously if the paint looks cheap or is a brand you're unsure of, maybe go for a slightly more expensive one. That's what has worked for me.
I had typed a bunch more useless information, but I erased it and tried to find a real guide, which will help you much more. Of course this morning things aren't working out so well, and I can't find a good painting guide. Hopefully someone else will post one. Just remember to take into account that whatever guide it is, they are most likely focused on achieving a glossy finish, so you can skip some of their steps if you don't want the gloss. This will likely save you alot of sanding and polishing.
