My Book Essential- need to set it up on my Mac


I was wondering whether somebody else had encountered the same issue and how did they resolve it.

My iMac had to have its screen replaced as it froze the whole system. The guys at Apple wiped out the hard drive, understandable :smiley:. Now, it asks me to set up  my WD My Book Essential, but I already have a lot of data there.

My question is whether by setting it up it would automatically delete all the info there or it will preserve it. I feel a bit uneasy doing so in case I lose everything. The iMac’s harddrive won’t be able to back it up- it is much smaller. 

I can access all data on it, but I’m concerned it is affecting the performance of my Aperture program. Also the light indicators are not working, which I guess is due to not being set up :cry:

Could anybody help?

 Many thanks

I you are using smartware to backup your files it wont delete any of the files in the my book, I believe is the same with time machine.