sharing internet ect between ME & xp on same harddrive

hi

i have a pc that is setup to run both ME & xp (xp as the main os) i want the internet to work on both, do i need to run the setup for the modem on both partitions?

same with things like virus/spyware software does in need to be on both partitions for it to work ?

while i'm on this with this system, is there a way to make it boot straight into xp with an easy way to switch over to ME when needed?

thanks