Windows 7 Student Discount Limitations
You should always understand the limitations of any deal, and this is true with these student offers.
Note that you need to be a student actively enrolled in an appropriate program and you will usually only be allowed to purchase one set of software using the school's discount. Using your discount to purchase the program for others would count as a violation of the terms, so don't try to arbitrage your offer.
Also be careful when downloading. You usually only get one or two shots at your download. Make sure that you have enough room on your computer for the files before you start, unless you really enjoy emailing support to have download limits raised.
Note also that it seems that a fair bit of the discount comes from avoiding packaging and formal distribution. Most of the best deals offer major discounts if you choose to directly download it and burn your own CD or USB drive. If you're comfortable doing this, or following the instructions that they send, then it's a good deal and can save you a fair amount of money. There are usually options to get a real CD sent to you in the mail, but you'll have to pay around $10 more for this convenience. It's ultimately up to you.
Also note that these are almost exclusively upgrade versions. These are not full installations and you may run into trouble if you try to use these versions on a clean and new computer. You will need to own a license for either XP or Vista to be eligible for the deal.
Windows 7 is a genuinely good operating system, and I personally feel that it's worth upgrading. That said, just keep these limitations in mind before you commit to your purchase. The student discount for Windows 7 is nice, but it cuts deeply into the license and forces you to do a few things for yourself.