If you delete the users from the Accounts prefpane, their user directories are either enclosed in a disk image, or deleted outright. There are no orphaned files associated directly with their accounts.

I can't tell from that response if the deleted users' files would be deleted or not, or if they would become inaccessible. Please expand on that answer.

If you delete a user's account via the Account Prefpane, (depending on which course you choose):

1)
Their home directory (/Users/foo/) is put into a disk image and that disk image is moved to /Users/Deleted Users/, subsequently, their home directory (/Users/foo/) is deleted. This preserves the data on a disk image in case you ever have to go back for information in their home directory.

OR

2)
If you choose "Delete Immediately", then their home directory (/Users/foo/) is immediately deleted.

Make more sense?

I deleted the user in question, but the dialogue box didn't explicitly say that all their data and files would be deleted. Now I have a very angry spouse. Is there some way to recover that data?

1) What version of OS X are you running?

2) I'm confused, weren't you trying to delete a user and remove their requisite information? Why are you now asking to restore data?

3) Assuming you're running Panther, which selection did you choose when you deleted the users? The "OK" button or "Delete Immediately" button?

Not Panther, it is 10.3 I think. I hit the "Delete Immediately" button, thinking that would delete the user and save the data. Wrong. The dialogue box didn't say that explicitly. I also attempted to rename the administrator, but that messed up the computer so badly that I had no internet access, no mail. Now AppleCare tells me that they don't support that, so I had to take the iMac to an Apple store

Panther is 10.3.x

My earlier post told you what the "Delete Immediately" button did.

I'm sorry, I guess that wasn't specific enough. By "their home directory is immediately deleted", I meant everything in the user's home directory is immediately deleted, not saved. You should have been clicking the "OK" button.

Renaming a shortname of an account is always a bad idea if you don't know what you're doing.

Sounds like what you need is a backup solution. That way you could have easily recovered from all this. Cloning your boot disk to an external firewire hard drive is an inexpensive backup solution. Using a low-cost product like Carbon Copy Cloner or SuperDuper, you can automate a backup that will copy all data from your boot device to another device (firewire drives might be easiest for you). This copy will be bootable, so if everything on your boot device gets fried, you can always fall back to the copy. Naturally, this system isn't infallible and you should do some research first, but everyone needs a backup solution.