Well, my brother had a Dell for a while (I don't remember the name, but it was like the first 12.1" one they put out), but about a year or so ago he bought a MacBook Pro, and he says he infinitely prefers the Mac. Dells are sort of well-priced if you can find the deals they seem to constantly have going on, but my experience with looking into buying them is a lot of the time they come with lackluster base settings, and the upgrades are ridiculously overpriced. With stuff like RAM you can do it yourself, but that's not always the case. I don't know much about the current line of Dells, but MacBook Pros have pretty speedy processors, GPUs that are significantly better than what you typically find in a notebook (maybe the XPS laptops are like this too, idk), they by default come with a pretty good amount of RAM, and obviously large hard drives is a given. I'm positive you can get one under $2000, especially if you can work a student discount in there.
Plus, it's really nice to have the screen size of a 15.4" without having to deal with the weight that usually comes with it, as the MBP's surprisingly light, and even though it's bigger than a 12 or 13" laptop, its dimensions aren't substantially larger, especially its thickness or depth or whatever. Also MAYBE of note is the fact that it's easily got the best keyboard I've ever used on a notebook and the keys light up in the dark, which is actually pretty handy sometimes, and it's one of those things you don't realize you appreciate so much until you've had it. The screen's pretty nice, too. His old Dell and some other ones I've seen have that reflective coating shit on them, and idk if they're still doing that, but it's really annoying outside or in bright rooms. We're both fans of OSX, and in fact I'd probably opt for it over Windows if I had the cash around to buy a decent Mac, and I'm pretty sure it can easily do all of the things you're talking about doing (there's Bootcamp or whatever it's called for partitioning your drive and running Windows on one of the partitions, if gaming is really your thing. From what I saw just playing a few, it worked at what seemed to be full speed, and it was definitely better than whatever inter-OSX Windows emulation people had to use before).
So yeah, maybe consider one of those.