Writing down notes on research and work conducted in the work place. Like microsoft word.
Having images in beautiful colour and resolution. For motivation mainly.
Internet surfing when a Wifi / Cable is not available.
Taking pictures of work sheets on the desk.
I am not interested in Games, Movies, Music.
Help? I can't decide.. I do love the idea of a pad in your hands. Feels futuristic.
Honestly pretty much any tech ranging from any notebook, tablet, or data phone will do what you need.
Though you will not be getting Microsoft word with an apple product. I can tell you that with a large amount of confidence.:P
I'd go with something not so expensive and bulky as an iPad or Mac. Probably an android tablet would work. You could always go into a store and check it out.. or shop online. Either way be sure to read some reviews on the product before you purchase it. Just to be safe.
Of course there is a OS X/Mac native MS Office and almost all other applications you can think of. In rare circumstances you'll find some Windows-only stuff (mostly high-end specialized programmes like SPSS and SAS - which are now both out in native OS X versions) but then you have the option of using critically acclaimed emulators such as Wine to run Windows applications or just simply keep a small Windows partition on your mac and dual-boot. It's been 10 years since applications and compatibility was an issue.
I was a long time mac user, but switched back to Windows last year - if you intend to be using your laptop on battery a lot and if you plan on bringing it out (to class or work or whatever), I'd definitely recommend a Mac. They are a bit more pricy, but will last you a lot longer before dying plus let you do whatever you need to do with a lot more grace and ease (which in turn improves productivity). If you want to game or don't plan on a lot of mobile use, you can opt for a Windows laptop (the sole reason why I switched back).
As for tablets there's only really the iPad if you want something decent. Plus for some reason the usual price gap between apple and non-apple products is relatively smaller on the iPad - I guess they really want that market. However you will get annoyed with using the keyboard (the tactile feedback (or lack of) when you type on a flat even surface slows down typing significantly and will annoy you) so for actual work I wouldn't use it.
As an ipad3 owner, i can say that the applications you can do with the thing is immense. However, for the stuff you mentioned, it may be a bit expensive.
Ipad is excellent for mobile solutions, from using for simple web stuff to controlling your mixing desk remotely in a studio. I was an apple hater but i have to tell that i am in love with the new ipad.
Again, its price is high for your needs though. For me, it was cheap. It depends on your budget and preferences.
An example: i buy computer music mag, future music and sos mags for my studio. Buying them from newsstands costs 60 usd per issue. Buying them on ipad is like 15 bucks. The annual difference kinda covers the expense for an ipad, when you add rhe versatility of the machine. And no, some of the things i do in the studio cannot be done by other tablets. No power or applications.
Literally a week ago I found an Asus tablet in a park, without any information about the previous owner whatsoever, so I assumed control of it. It's rather nice uses Android, perfect for writing text files, browsing the INTRAWEBZ, even playing GTA 3, a quick google search revealed it costs something like $300, so for a tablet I think that's quite low range but since it was virtually free, I'm quite happy with my find.