consort, Welcome to the forum and to the world of Tools Before buying any power tools I suggest a good set of hand tools. What tools do you have now?
An ATX Computer Case is not a good starting project because they are made from metal because they need to hold a lot of standard size parts with wiring between the parts. They are also very cheap so they are really not practical for a DIY project.
There may be other computer related projects that would be easier to start with for example some kind of stand. Different kinds of projects require different tools but the basic hand tools remain pretty much the same.
I am not familiar with Partex. Is it a USA product?