How can I reset my phone without losing everything? I have a Samsung Galaxy S I9000, it keeps lagging; freezing and turning on and off by itself. I want to reset it, if I do will I lose all my photos, contacts etc etc..? I can't figure out how to transfer everything on to my SD card.
If you do a factory reset, your SD card will not be touched.  Your pics, etc will all stay put.  If you've selected your Google account as the default way to store your contacts, they will all repopulated from Google after you set up your phone.

If you want to be sure you're saving settings, etc. download Titanium Backup from the Google Playstore and do a full backup.  After you've reset your phone, reinstall Ti and then do a restore from back up.  Super simple!