Before upgrading to Microsoft Windows Vista, consider this eye-opening research by William Blum:

Microsoft and the National Security AgencyI have long felt that the American media's gravest shortcoming is its errors of omission, rather than its errors of commission. It's what they leave out that distorts the news more than any factual errors or out-and-out lies. In January the Washington Post reported that Microsoft had announced that its new operating system, Vista, was being brought to us with the assistance of the National Security Agency. The NSA said it helped to protect the operating system from worms, Trojan horses and other insidious computer attackers. "Our intention is to help everyone with security," said the NSA's chief of vulnerability analysis and operations group. The spy agency, which provided its service free, said it was Microsoft's idea to acknowledge NSA's role, although the software giant declined to be specific about NSA's contributions to Vista.[12] What the Post -- and most likely the entirety of mainstream American media -- do not remind us of is what came out in 1999 and 2000, although it's all over the Internet. In September 1999, leading European investigative reporter Duncan Campbell revealed that NSA had arranged with Microsoft to insert special “keys” into Windows operating systems, beginning with Windows 95. An American computer scientist, Andrew Fernandez of Cryptonym in North Carolina, had disassembled parts of the Windows instruction code and found the smoking gun -- Microsoft's developers had failed to remove the debugging symbols used to test this software before they released it. Inside the code were the labels for two keys. One was called "KEY". The other was called "NSAKEY". Fernandez presented his finding at a conference at which some Windows developers were also in attendance. The developers did not deny that the NSA key was built into their software, but they refused to talk about what the key did, or why it had been put there without users' knowledge. Fernandez says that NSA’s “back door” in the world’s most commonly used operating system makes it “orders of magnitude easier for the US government to access your computer."[13] In February 2000, it was disclosed that the Strategic Affairs Delegation (DAS), the intelligence arm of the French Defense Ministry, had prepared a report in 1999 which also asserted that NSA had helped to install secret programs in Microsoft software. According to the DAS report, “it would seem that the creation of Microsoft was largely supported, not least financially, by the NSA, and that IBM was made to accept the [Microsoft] MS-DOS operating system by the same administration.” The report stated that there had been a “strong suspicion of a lack of security fed by insistent rumours about the existence of spy programmes on Microsoft, and by the presence of NSA personnel in Bill Gates' development teams.” Microsoft categorically denied all the charges and the French Defense Ministry said that it did not necessarily stand by the report, which was written by “outside experts”.[14] In case the above disturbs your image of Bill Gates and his buddies as a bunch of long-haired, liberal, peacenik computer geeks, and the company as one of the non-military-oriented halfway decent corporations, the DAS report states that the Pentagon at the time was Microsoft's biggest client in the world. The Israeli military has also been an important client. In 2002, the company erected enormous billboards in Israel which bore the Microsoft logo under the text "From the depth of our heart -- thanks to The Israeli Defense Forces", with the Israeli national flag in the background.[15] [12] Washington Post, January 9, 2007. p.D1 [13] Duncan Campbell’s article of September 3, 1999 can be found on the website of TechWeb: http://www.techweb.com/wire/29110640 [14] Agence France Presse, February 18 and 21, 2000 [15] To see one of the billboards: www.inminds.co.uk/boycott-news-0022.html