Ebooks for study

Do you use Ebooks as textbook? What are you thoughts? Do you prefer physical copy or virtual copy?

Ebooks and textbooks, many great text books are still not available as ebooks, for example the fundamental books we studied in colleges. My personal Library consists of 100s of physical books and 1000s of magazines from various technology domain. My ebooks collection will soon occupy a hard disk of 1TB. That said I use books and ebooks depending up on the situation. Both have its own pros and cons. Here is a great comparison between Ebooks and Books

Ebooks were cheaper than text books! Just kidding:)
I love text books since I hate sitting with computer for long time. I have a large text book library containing 100s of engineering study books.

I prefer having the physical book in my hands and being able to highlight the physical book. I know that you can highlight in ebooks, but for some reason...I just don't retain the information as easily. That being sad...if I have to buy a book, I will most likely buy an ebook simply because it's cheaper. Also, it is more convenient to carry around school.