I am looking to add memory to my sony vaio lap top primarily to store my i tunes music. I have two drives on my lap top . My C drive has onyl 12% space left even after taking music and photos off etc. my D drive has my i tunes on but only has 16 % left. i cant defragment my C drive because you need at leadt 15% to do it. So an external hard drive seems the only option. Any ideas will be very welcome as to what sort and how big etc.