Yes but before you do transfer your items to your computer first, you can go that by going on iTunes going under file and near the bottom then you can transfer because iOS 5 will delete your apps and music and media but not your pics or contacts and stuff like that.
Just plug your device to your computer and go to iTunes. It's a really long download but totally worth it. Just remember to back up all your apps and music. It will go back to factory settings after the download so you have to reinstall those from your backup.