Quick story. Friend of mine, way back in law school, had a three-year-old laptop that she used for class. Two weeks before exams, the hard drive failed and she lost everything -- from notes to outlines.
Another story. Myself, I had no laptop. I could not afford one. I did the paper-and-pen note-taking, then typed my notes each night, for a few weeks until the Intel Atom-based netbooks were released. Of course, then I had to hear jokes about my "Game Boy" laptop from the class gunner.
The sweet spot, for most of you, will lie somewhere in between.
You may be able to use that three-year-old laptop, but do you really want to risk it going kaput in the middle of finals week? While we wouldn't recommend going through three years of school on a netbook with an 8.9" screen (memories), a nice, mid-range laptop should suffice.
Personally, after the abomination that is Windows 8, I'm leaning towards a Macbook Air for my next purchase. MacBook Pros are overkill (and quite frankly, would be an idiotic purchase until Apple updates their processors). Whether you choose Windows, Mac, or Linux, look for an Intel Haswell processor, as these new chips last all day long.
Yes, a smartphone is a near-necessity at this point. Between organizing your class and study session schedules, and having a music player for your trips to the gym or late-night cram sessions, your phone will be your best friend.
Most of you already have smartphones, but if you are looking for a near-term upgrade, the new line of iPhones is expected to be released next month, including a rumored cheaper-than-usual variant. For Android folks, you can't beat the value of a Nexus 4, at $300 contract-free.
Remember that devastating hard drive crash we mentioned? The effects could have been mitigated by using a cloud storage drive. Unfortunately, DropBox had not yet descended upon us back in the fall of 2008. Today, all of your notes should be saved in your local auto-syncing cloud storage folder.
You do not need one. There are nearly no truly-useful apps on a tablet that aren't also on your laptop. Dictionary apps can be found for free online. Case briefs too. Some, but not all, study supplements are available on Kindle, but do you want to buy e-book versions that are more difficult to notate and more importantly, to sell back?
Android tablets and iPads are great for study breaks, but when it comes to productivity, your best bet is your laptop.
Before I sprang for my trusty netbook, all of my work was done on my at-home dinosaur of a desktop. Desktops are for two types of people: video encoders and gamers. No one else needs the dedicated video cards or immense power of an eight-core processor.
With today's chips, a laptop, while costing a bit more than a desktop, will have near-equivalent power and will allow you to go portable for study groups or marathon library sessions.