2. For NTFS format the partition with the virtual HDDs with 64-bit cluster. Keep the partition not fragmented
2. For Linux - from my tests I have found that reiserfs is the fastest filesystem for holding VMs
3. Always allocate HHD space for the virtual disks
4. Do not set to the VMs more then 1.5 GB RAM (independently of the host's RAM) especially when several VMs are running simultaneously (see discussing "More then 2 GB RAM for XP virtual machine" in VMWare Worskation beta community for more details).
5. Always install the latest VMWare Tools
6. Enable write cache for virtual HDDs
7. Keep the partitions of virtual Windows machines not fragmented
8. Do not run the VMs in the debugging or logging mode
As far as the LastAccessUpdating, this is more actual for the guests. Host has just few files those correspond to each VM. It's not a big problem to update the LastAccess time for these few files.