As has been pointed out the Windows 7 will cost you $100+.
At $250 you're going to get crap. For $250 I'd just go get used, I think you would get better bang for the buck.
Given your parents' VERY casual needs, consider Linux instead. A distro like Mint is well supported, can be reskinned to look identical to Windows (your parents need never know!) and will perform very well on the hardware you will inevitably procure for this. It's also free. 4GB of RAM is overkill, don't need it, 2GB or even 1GB will be perfectly fine unless your parents are wrangling immense spreadsheets (in which case, go for 2)