slow Wifi

New to Apple and switched from PC to Mac. Have to say I love my Macbook pro and the rest of my Apple products. The one think I hate is how slow my internet is on wifi. Half the time I cant open a web pager or get message loading took to long. I have tried everything from resetting router, trying a different computer on net. My girlsfriends PC laptop works great, yet my Macbook is so slow..Please Help.