Here are my thoughts.
1. You don't need a PDA. At all. Please note that if you have one, it will cost you 2-3x as much to get your drug and clinical references in software form than it would to get books and carry them in your coat pockets.
2. You don't absolutely need a computer if money is tight, but it is handy. My med school is extremely email dependent, which means that if you don't have a computer and Internet at home, you have to take yourself to the school's computer lab to check your email and do your online stuff. That is a pain. After a month of not having one, I bought a laptop a month into first year and got internet at home. But your computer does not need to be a laptop. I very rarely took it in to campus -- mostly it just sits in my apartment all the time.