Solidworks is a great piece of software. It is hard to make organic shapes like the Dr has mentioned. BUT Solidworks is a very powerful parametric modeling software and if you are looking to get your feet wet it is a great place to start.

I use PTC Creo 2.0 and it is similar to SW in that is is your typical parametric modeling software but it does have a feature where you can take a blob of clay basically and mold it and make very organic shapes quickly and easily. If you have access to SW then it will be great for what you are probably needing. If you are looking to buy some software and drop major cash then look at Creo.