My Product key says it's

Question

My Product key says it's invalid and i need a new one I bought a vista home basic compuer and later I used the upgrade disk for Windows Vista Home premium ,but it says i need a new product in 4 days.And i dont want to call microsoft,all i want is a product key or something that aciveates it.I instaled this thing wich tells you your product key but when i entered the key it said it was allready in use please help.