Migration of VMs from older version to newer one--issues

Hi guys,
First posting is about an issue which all those first times dont know ,
Migration of VM from older ESX version(say 2.5.x) to a newer ESX version(3.0.1)- the migration procedure we adapted for this is
1. Take down the VM using GUI(VC or VIC) before that take a note of all the settings of target VM.
2. COpy the folder which contains VM files from ESX2.5.x host to ESX3.0.1
3. Create a VM in ESX3.0.1 and associate the .vmdk file that you have coiped from the ESX2.5.x host.
4. check that all the settings and change as per the older VM setings and then power on the VM.

Well this seems to be easier than i have taken to write it hear, but,.........
Try the same for a VM having two hard disks- U will not able to associate the 2nd hard disk to this VM, it will not highlite the option of adding new harddisk to this VM
we searched the net for solutions but ended up with all rubbish.
Then one fine day we found that there is a hardware upgrade that needs to be done which can be done on VIC simply by right clicking on the VM that was migrated and select the option "upgrade VM hardware". Thats it now we were able to add the 2nd hard disk also.

Thats it issue is resolved......