If the partition(s) on the disk is not changed/formatted then you should be able to use it in the other system with no problems.

If the disk is a total of 8GB and it's all in the one partition (excluding any small partitions possibly used for volume management) then moving the disk is simple.

If you are using a volume manager, like Vertias or DiskSuite, then you have some reading to do on removing (exporting) the partition to the new server.

Please post if you are using any volume management software and the layout (partitions) of the disk being moved. Also the OS version of the system the disk is in and the one it's going to.