This is an example where prescriptive grammar fails us (in practice I mean). Generations of people have had drummed into them that they must say "John“John and I went"went” not "Me“Me and John went"went”, because of some supposed rule imported from Latin. (SeeSee¹ Emonds, J. "Grammatically“Grammatically deviant prestige dialect constructions." ”A Festschift for Sol Saporta. Ed. M. Brame, H. Contreras and F. Newmeyer. Seattle: Noit Amrofer, 1985, for why "John“John and I went"went” cannot be part of any naturally learnt variety of English).
But "Sarah“Sarah and we/us"us” is not frequent enough that phrases like it often come up in pedagogy, so we are left with two unpalatable alternatives: "Sarah“Sarah and us"us” must be wrong because "Sarah“Sarah and me"me” is wrong; but "Sarah“Sarah and we" doesn'twe” doesn’t sound right either, and we don'tdon’t know what to say.
Emonds discusses a number of more complicated cases where people are often unsure about the application of the rule, but I don't remember whether they include this one.
[Edited[¹ Edited to correct title of paper and provide proper citation, 3 December]December 2010. Text available at fine.me.uk, February 2011.]