I can't say much about the HD I have to 60G 7200RPM one. The Backpack is way too big for everyday use. I have one and if you were going to use to go to a lan party it may be ok. I have enjoyed my XPS2 very much.
There are several threads on this issue that have some great info.
I used to carry my AW A51 m in a targus sport backback my new XPS2 did not quite fit. I decided to get another case at Best Buy. I chose this...
Hello I am not sure if this is what you are looking for but I have used a Targus Podium coolpad. It holds the laptop at an angle by raising the back of it. It not only helps in cooling but it has saved my A51m from several spills.