Extending Partitions Using Comuter Manager

Hi,I have vista home premium and am wondering how to make a partition bigger using computer management, I know I have to shrink another partition, Then I have unallocated memory but it wont let me extend the other partition, that option is blacked out, does anyone know what to do? I am currently copying everything from my fs partition to an external hard drive, then I will delete the partition, shrink the other partition and just create a new one with a bigger size then copy everything back.