You can easily move the virtual disks from the old server to new server without problems, but first make sure do the following:
1. remove any snapshots on old virtual machine;
2. shutdown the old virtual machine;
3. take note of the datastore and folder where the virtual hard disks is stored on old virtual machine;
4. remove the virtual hard disk from the old virtual machine; (make sure do not select the option Delete from Disk);
5. attach the old virtual hard disks on the new virtual machine, just clicking edit settings, select add virtual hard disk, choose use a Existing Hard Disk and point to the datastore/folder of the old virtual hard disks.