Microsoft Let NSA Spooks 'Enhance' Windows 7
It’s a safe bet that NSA helped Microsoft make Windows 7 more secure, not less secure.
Something that few people have pointed out is that this isn’t the first time the NSA has contributed code to widely-used operating systems. One example is SELinux, an NSA-originated security extension to Linux that has now been rolled into the Linux kernel. My own impression is that SELinux makes a significant contribution to the security of Linux systems (at the price of sometimes being a pain in the ass).
Of course, Linux is an open-source operating system, so the developers who decided to roll SELinux into the kernel had the chance to minutely inspect every line of it to make sure that it really did what they thought it did. If you’re paranoid, you can too. Whatever the NSA and Microsoft did together happened behind closed doors, so only they know what the NSA-supplied patches really do.