I have recently purchased the Nokia C5-00 phone and I'm looking to upgrade my MicroSD memory card up to 4GB...Memory card manufactures are says that it can handle 4GB class 6...what is the meaning of class 6 .and there is another classes also class 1 ,class2,etc i want to install class 6 memory card.is it support my Nokia C5-00 ..thats all i want to know..