Workstation 8- Upgrade VM Hardware Compatibility?

Hi;

   I was wondering what the 'usual' procedure is when you upgrade from Workstation 7 to 8. Is it expected that you would normally keep the VM 'Hardware compatibility at the old '6-7' level, or is it expected that you would usually upgrade the old VM's to version 8? (At least presuming you don't have any issues where you need to maintain compatibility with other VMware products...).

  I presume in either case you would normally install the version 8 tools. I have Windows 7, Windows XP and Linux Guests.

  Thanks;

       -Greg