I'm pretty new to the site myself, and a Boxster owner for less than an year, so I don't have a lot to contribute. But I can give you a couple of thoughts.
- In 2003 the rear window became a standard feature. Prior to that year, it was an option. I get the impression that most people prefer the glass window (I do).
- I think everyone will agree... Have the car inspected at a Porsche dealer. I did. Even so, my ignition switch is having fits (sounds like a pretty common problem). The guy I got it from is going to split the cost of the repair.
- Finally, make sure it is really what you want. I think that all Boxster drivers will also agree that a Boxster is a car for cornering and handling, not racing down a streight away. This forum (and others like it) are scattered with posts about making a Boxster faster. The Boxster is quick, and many threads can help you make it quicker. But, from what I read, if you want to go 0-60 in 4 seconds, it ain't going to happen. Without major engine changes (and a lot of $), you are not going to get a huge boost in power. (That doesn't mean I have not considered some mods for my car, I have indeed. But I am very happy with it the way it is.)
Good luck.