Hello...
Wish I could help with the S40 query. Sadly new to the forum and Volvo's.
Might be worth you looking in the specific S40 (select models dates you like) and read the buying guides etc.
http://www.volvoforums.org.uk/forumdisplay.php?f=17 = S40 up 04 forum
Grand job on the Vectra btw!