Well, I'm not up to speed on the latest and greatest graphics cards. So you're on your own in that department. Most of the new higher end laptops come with decent ones anyway. It's only if you need the really sick ones that you have to look closely (look at the specs just the same, but my point is you shouldn't have trouble getting one with a good graphics card).
I doubt you'll need 8GB of RAM just for office tasks like that. I've tried to max out my 3GB of RAM in my Dell with a crapload of programs open (about 30), but it barely creeped over 1.5 (normal usage for me is 1GB). Gaming might need some RAM room to breathe, but you should still get by with 4GB. The processor and graphics card will be more of a hindrance than the RAM anyway. You can still upgrade the RAM if you want, but it will likely be overkill. I'm not a gamer, so I can not say for sure. You'll have to make that call yourself.
Well, with last year's technology in my Dell (6-cell battery), I can achieve all day computing with the right power settings and smart usage. With a good reputable brand and up to date battery technology, there is no reason why you couldn't get a day's worth of computing done on a single charge with a 6-cell. But let me warn you, carrying a big heavy laptop around campus all day will get dull quick. That's why I bought my netbook. Not trying to discourage you, just letting you know how things are. Carrying a couple classes worth of books plus a laptop all day can really put a strain on your back. I thought my hiking gear was heavy until I started college....
I wouldn't buy a new PC these days with anything less than a 2.0GHz processor (unless the budget dictated otherwise). The new i7 and stuff can get some pretty high speeds, but you have to remember that the larger and faster the processor is, the more battery juice it will use. You might have to compromise in the middle ground of battery size and processor power. A Core2Duo or Pentium would serve you well.