You know, I had a friend who downloaded CS2 less-than-legally, to take her time learning the program, to become really proficient with it, and then once she started using it for income purposes rather than a hobby, bought CS4. I don't know if you would feel less guilty doing this or not, but I (and no, I'm not the law, I imagine they'd have far different things to say on the matter) never faulted her for this. :)
If you have any other questions about the program, let me know! I'm still running on CS2 (plan to upgrade to 5 when it comes out), so I may or may not have some of the CS4 tools, but I'm happy to help when I'm able!