Your home network getting really big?  Maybe it's been a while since you have done a backup?
  This is an interesting article on what NOT to buy from a user.
http://www.notesfromatooluser.com/2007/09/using-network-a.html

  (Me.  I invested in a USB External hard drive called MyBook that (1) extended the life of our 333MHz 4Gig Laptop that is the main PC in the house because it lives on the coffee table in front of the TV, how sad is that! … and on this laptop is only applications since we moved all documents onto the external drive.  And (2) it is our backup solution from any PC in our home network.  (  No, we are not doing automated backups yet, but that will be coming. )

  The MyBook at CompUSA in Delaware: $120 for 500 Gig http://www.compusa.com/products/product_info.asp?pfp=cat3&product_code=338831