I am about to purchase a few computer programs that will help me in my structure building and general modeling. The problem is, I don't know what to look for. So, I am looking for some suggestions of the computer programs that you find most useful in your activities with modeling. I was thinking about a vector-based drawing program and software that I can use to edit and manipulate photos. What do you recommend that is a very good value? One more thing: My computer is running Windows XP Pro.