I think those systems qualify you to use the upgrade CD but...

Any computer that's running one of these systems (especially Win95),
is likely to be old and slow enough that Vista would be a horrendous
overload.

MS answers yes;  but most experienced users say this is
the wrong question.   The right questions are:
1.  What do we want to do that Vista will enable
and that Win95/98/Me does not?
2.  If we upgrade to Vista, will performance be acceptable:
2a.   by comparison with our Win95/98/Me PC?
2b.   by comparison with a PC designed for Vista?

The two are related.  E.g. are "3D menus" something
you really want?  And even if not, do you want to pay
for 3D menus (in CPU cycles etc.) when you do not
actuallly use or need them?

Whatever you mean by "migrate" (officially upgrade - probably
not, use the same machine - no way, unless you bought it a week
ago, etc.) it would probably be more enjoyable to pull all your
fingernails out with a pair of pliers, one by one.

Hmm - what I meant to ask is it possible to transfer settings, emails etc
from one pc using win95/98/Me to another running Vista
My apologies for the confusion - entirely down to my ignorance
Regards & TIA