Hi again, and thanks for your quick responses. I am using the addition of an extra filter on the makeprg, as suggested. Here's what I use (I'm setting it buffer local, for other reasons):
let &l:makeprg = &makeprg . ' $* \| sed -e "{
s/\(\w\)\:\\\/\/cygdrive\/\1\//;s/\\\/\//g }"'
which converts X:\ to /cygdrive/X/ and all \ to /.
Thanks again,
Tom.
