Change just Oil or Oil and Filter

2003 Boxster, its been garaged all winter (chicago weather makes me cry at times), but its almost time to uncover it for the season =8||. Its got 9400 miles on it and has not yet had any maintenance. (yeah it is babied - during the winter only though! ). I at least want to replace the Oil (even though maintenace says it is good up to 15Kmiles). Is it ok to just replace the oil or should i change the filter. I am trying to talk myself into just changing the oil as i'll be doing it myself, (its still cold even in the Garage).

thanks for any replies..
-ody

our dealership recommended every 7500 miles or 6 months. its better to change the oil and filter but anything is better than changing the oil every 15k. make sure you use mobile or castrol synthetic oil.