install from windows or bootcamp

I have a windows 7 oem iso file.
I want to install it.
I have vista home premium installed.
So ,Do I just insert the windows dvd in windows vista and follow the instructions(ie. install on bootcamp partition) or should i start all over again (ie. delete windows vista partition and make a partition and start again)

Currently all the drivers are working perfectly .
Will they work perfectly with 7 as well?
Eg. low volume..which i fixed reading a thread on this forum..will i be able to do that on 7.