need dummy instructions

i would like to dual boot win7 and ubuntu 9.10 i have win7 installed .i have the following partitions:
system=100mb
C:=97,56gb boot page file , crash dump, primary partition
D: 39gb primary partition [empty this is where i want to install ubuntu]
E: 329gb logical drive [ i would like this to be a shared drive for data]
need some help in how to do this as i have read that it can mess up the MBR what ever that is.
please dont answer me with “google you fool” i have but it wasnt clear enough for me.
thanks.
PS
i also have a external 320gb seegate free agent harddrive i could use if its safer to put it on a seperate harddrive.
Answer #1
install 7 then install ubuntu yes its that easy.
Answer #2
can i install it on the external drive?