For my White Macbook I use SimpleTech Cherry Red Model. I bought it about a year and half ago and it has not given me any headaches, unlike the seagate one I had previously. For the Cherry Red model, you get 320 GB storage, If that is not enough, there are other models from SimpleTech.
I like their products because it is mac-friendly, and mainly products are tailored to windows users and so it is hard to find a nice mac compatiable product.
My SimpleTech drive works great with TimeMachine, and works efficiently but it one negative about it is that it uses up 2 USB ports
since the white Macbook only has 2 ports, I can not plug in anything else in the USB ports if the SimpleTech is plugged in.
Also you can use it to store other files along with your time machine backups and so it can remove some of the hard drive clutter if your are running out of hard drive space.
So all in all, I think this product deserves a 5/5 because after all the headache the Seagate product gave me, this product is heaven.