1.3 Is Coming Out Today. Your Probably Excited But... If You Update You Wont Be Able To Access The Server. Either Dont Update, Update to 1.3 or copy Your 1.2.5.jar to copy it for windows go down to the Windows icon u should have Run Or a Start Search type in run or the start search "%appdata%" click Roaming go to .minecraft go to bin Right-Click Minecraft Or Minecraft.jar paste it somewhere else then your done. We Will Update To 1.3 In a Few/Couple Of Days, Where You Will Be Able to Play With 1.3!
EDIT: Lock And Archive When Kreatious Updates To 1.3