Windows 98 User loses ISP subscription July 2006 loss of MS support

I got a call today from a friend who is looking for guidance.
She has just spent three months recovering from an auto accident so has been
out of circulation for awhile. She has an old computer and has been running
Windows 98, mostly for email, and is not knowledgeable about computers.

During her absence her ISP has received its monthly payments, but she has
been given a notice from ISP that is something like this (I haven't seen the
actual info yet):
Windows 98 is no longer supported by Microsoft.
Your password (is gone) ? (is no longer valid) ? - not sure how it's worded.
And there was a suggestion that she go over to Windows XP.

This is what I make of it.
(I already know Microsoft no longer supports Windows 98 as of this past
summer). My supposition is that, since Windows is no longer supported, that
there are no more security updates; that since the ISP probably has covered
itself by security at the server that they aren't interested in "maybe
contaminated" Windows 98 output through their server.

I hadn't heard it like this before, but sounds most probable. Does some one
know, specifically, that this is a common occurrence for Windows 98 users,
since the loss of update support?