Hello Paul,
You are most welcome.
I think I will reverse the order of things and do Lion and then Fusion 4 more likely at some point in the future.
That should be fine, as you might have read in the knowledge base article I referred to, they actually advice you to do a "fresh" install of Fusion after the upgrade to Lion. So upgrade to Lion, then rerun the install (Fusion 3.1.3). You will get asked if it is OK to uninstall, the uninstall by itself is harmless as in that it will just remove Fusion, but leave your virtual machines alone. Then install Fusion again after the install so that it is made sure that everything is OK.
When you are ready for the upgrade to Fusion 4 and if you do use the shared folder option to share files with your host, then there is a current issue with Fusion 4 and Windows 7 that causes the dock to run into high usage (or your VM to stall with the windows explorer process eating up CPU) There is a workaround for that. But as you mention "will upgrade at some point" .. it might just be resolved by that time.
I'm not sure if everyone sees the issue, but I am seeing similar issues here with Fusion 4 and Snow Leopard where the same work around with disabling the filesystem notification appears to help (I'm still testing the workaround on that part though).
Anyways..
Confirming for the newbie, by "full copies of the important VMs" you mean the xxx.vmwarevm files is that correct?
Exactly
For the 4 GB issue, appreaciate your comments. I'm a pretty lightweight user, I think, so will go ahead with the recognition that I may need to upgrade memory if there are major performance issues.
For lighweight usage you are most likely fine. I love the 8GB in my MBP, but can't say that I'm a lightweight user 
PS: If you like to tinker around with new operating systems (like the latest linuxes etc..) then you might want to look into upgrading to Fusion 4, also if you want to run Lion as a VM you would need that.
--
Wil