I dont remember exactly when they switched. But, I would make sure you buy one with the 4 year 50k mile warranty. That is a great thing to have when parts and repairs are so expensive.
You should be able to find a 2000 model for about 35k. I know thats more than you have now but you may wish to think about it. a good starting point for price ideas is the ebay link on the main page of this forum. it list all boxster from highest price down. If you dont see the link. just go to
www.boxsterforum.com
good luck. I think you will love your car when you get it