You've received lots of good advice already. I'll add some comments, as an owner of multiple Macs and Windows PCs over the years. I just purchased the 15 inch model - not the retina display (which I do regret, kinda, but didn't want to pay fork out the extra dough, and I wanted the optical drive in the "old" style for now).
Refurbished is your best bet if you are set on the 17 inch. I almost went that route, but find the 15 inch meets my needs and doesn't take up as much space.
If you go new, definitely check into the education specials that Apple offers. I'd also suggest you check
Best Buy if that's possible. There was a huge thread on the MacRumors forum about getting $200 off, and some also got a $100 gift card.
Same for software - check the educational discounts. If you have photography software on your laptop, there are some things to keep in mind. iPhoto works well for basic stuff, and it's free. Aperture is $79. If you use Adobe products, an existing Lightroom license can be used on the Mac version. For Photoshop, you will first have to convert your Windows license to the Mac license before installing on the MacBook Pro
AppleCare - the extended warranty is good to have. Check out places like B&H Photo and possibly
Amazon to purchase it for less than retail (although you may do better with the educational discounts). It's the same product, and gives you full coverage. I choose to forgo AppleCare and just rely on my credit card's warranty extension program. It's a personal choice.
If money is not a huge issue, consider the new 15 inch Retina display model. The base model is not much more expensive than the older style. The costs start adding up when you upgrade things like the hard drive, memory, processor.
Good Luck - I doubt you'll have much problem adapting to the Mac Operating System - it's much more similar to Windows 7 (and now 8) than it used to be.
You definitely pay a premium for the Apple products. I've gone back and forth, but find I almost never use my Windows laptop for more than a year before I sneak back to Apple
