New partitions created using Windows 2008 are correctly aligned. However, if you do an UPGRADE (assuming this is possible) and your partition was not previously aligned, it will not become magically aligned. I have had little success with running mbralign with a Windows 2008 partition, so make sure the partition is aligned before you do the upgrade.
Also, you may have limited success with P2V. I seem to recall an instance in the past where we ran P2V on a Windows 2008 server and it resulted in misaligned VMDK's which we didn't seem to be able to fix.