Hi MaryAnne,
You can purchase the King’s Quest games for a great price at GOG.com, and then you’ll have a legal copy and won’t have to worry about spyware and viruses.
GOG is a great source not just for many classic games, but also for modern titles as well. All of the games you can purchase on GOG are DRM-free.
Unfortunately, they don’t have the Laura Bow series yet, but they do have King’s Quest.
GOG has split the series into three collections, 1-3, 4-6, and 7-8 (Mask):
http://www.gog.com/game/kings_quest_1_2_3?pp=a0e3eab3c80118379cb2e1d7b163f82494430e03
http://www.gog.com/game/kings_quest_4_5_6?pp=a0e3eab3c80118379cb2e1d7b163f82494430e03
http://www.gog.com/game/kings_quest_7_8?pp=a0e3eab3c80118379cb2e1d7b163f82494430e03