The i7 6700 isn't a bad processor at all, I'm just saying that if overclocking is important to you, the i7 6700K is preferable for easier overclocking. While non-K overclocking is promising, it's still kind of early for me to wholeheartedly recommend it. If you want to save money while keeping your overclocking options open, consider the i5 6600K?
Passively cooled options are few and far between. What country are you in? From a quick search, the best options I can find are the
Asus GTX 750 and
Palit GTX 750 Ti KalmX. The Palit is the more powerful card, but only appears to be available in Europe. The Asus is available in the US, though. I imagine both should be able to handle 720p gaming just fine.
Otherwise if you want even more power, consider buying a regular graphics card but change the VGA cooler for a passive one.
Arctic Cooling has their Accelero S3 cooler which is fanless and can handle graphics cards like the stronger GTX 960 and R7 370, but keep in mind some graphics card manufacturers consider the warranty to be void if you remove the original cooler.
As far as I know, Microsoft's thinking is that they want you to upgrade existing PCs with older versions of Windows to Windows 10. The promotion isn't intended to allow users to score free/cheap copies of Windows 10 to install on newer PCs. They can't cover all scenarios, though. Yes, you can purchase Windows 7 and then upgrade to Windows 10, but if you're buying a new retail copy,
Windows 7 is actually quite expensive at around $140 compared to just buying
Windows 10 at $90. The cheapest option is to get a Windows 7/8/8.1 key from reddit for ~$15 and then upgrade to Windows 10. Let me post my usual disclaimer:
Cheap Windows licenses can be bought from
reddit's microsoftsoftwareswap for cheap, around $15 USD or less. Windows 10 licenses are also available for a bit more. These are most likely legitimate keys that are resold from educational programs like Technet or MSDNAA/Dreamspark. However, you are dealing with a person instead of a retailer, and informal Windows keys sales are not approved by Microsoft and probably breaking some licensing agreement, but it's not illegal. The risks involved are that the person could be selling you a fake or used key, or that Microsoft may refuse to give you support and/or deactivate your license and refuse to reactivate it. That's not very likely, usually it only happens if the seller and their list of sold keys was caught. We've had people here using those keys without issues for a long time and others who say Microsoft deactivated their key after several months. The 7/8/8.1 keys should be upgradeable to Windows 10, but confirm with the seller to be sure, of course.