Mr Red has no real answer but it has been mooted about making the second user as an Administrator. Worth a test, even if you don't keep it. You trust your wife don't you?
For Mudcat, an alternative browser would allow two people to remain logged-in (eg Chrome & Firefox)

As to my knowledge on PCs - I only know what I know, my Vista (ho ho) is not large.

Computers are a vast subject these days, and I doubt any one expert knows more than 20% (of a given OS!). It was reckoned that Win 98 represented a Million man-hours of coding. Take that to be before the security updates!

FWIW I still use a Vista laptop for off-line work, video editing eg. It is OK - just.