Seven perfectly legal ways to get Windows 7 cheap (or even free)

Annual subscription: TechNet Plus

Expires: No expiration date

Who's eligible: Anyone (international)

If you're an IT pro, technical professional, journalist, or hobbyist, Microsoft has a program called TechNet Plus designed to give you access to a wide range of evaluation software for a single annual subscription fee. The price varies by country, and also by whether you're purchasing as an individual or on behalf of an organization. In the United States, the price is $349 for the first year and $249 annually for renewals. (Both of those prices are for download-only access; if you want DVDs shipped to you, you'll need to pay a higher price.)

What you get for that price is access to a staggering amount of software, including just about every version of Windows (desktop and server) ever made, along with past and current editions of Microsoft Office, developer tools, servers, and much more. You get multiple activations for most products – typically 10 product keys for every Windows and Office edition. [Update: The number of allowed activations has been reduced to 2 per product for the most popular TechNet subscriptions.] You also get access to premium Microsoft support: two complimentary incidents per year.

The software and accompanying product keys don't expire. So if you decide next year not to renew your subscription, you can continue to use the software and keys you downloaded.

So what's the catch? Read the license agreement carefully! This software is NOT for use as a replacement for licenses on PCs you use at home or work. Here's what the FAQ says:

The license grants installation and use rights to one user only, for evaluation purposes, on any of the user’s devices, this may include devices at home. Keep in mind that you may use the evaluation software only to evaluate it. You may not use it in a live operating environment, a staging environment, or with data that has not been sufficiently backed up. You may not use the evaluation software for software development or in an application development environment.

For technical professionals who evaluate hardware and software professionally, or for hobbyists who want to play around with new technologies, this is a tremendous deal.

Annual subscription: Microsoft Developer Network (MSDN)

Expires: No expiration date

Who's eligible: Anyone (international)

The terms and benefits of an MSDN subscriptionare generally similar to those offered to TechNet subscribers, with a few crucial differences. The biggest difference is that MSDN is specifically intended for professional software developers. An annual subscription gives you access to a wide range of professional developer tools and pre-release products.

Every MSDN subscription includes access to the latest version of Windows with multiple activations. You can choose from different levels of MSDN subscriptions. The cheapest is the MSDN Operating Systems subscription, which costs $699 for the first year and $499 for renewals. It offers full access to Windows, toolkits, and SDKs. Prices go up for other editions: $999 ($649 renewal) for an Expression Professional subscription, for example, which is intended for designers and web developers and includes Windows, Office, Expression Studio, and Visual Studio Standard Edition.

Unlike TechNet licenses, which are strictly for evaluation, an MSDN Premium subscription specifically permits you to install and use one copy of the latest edition of Microsoft Office (currently Office Ultimate 2007), Project, SharePoint Designer, Visio Professional, and Office Communicator "for General Business Use … on one machine for any purpose."

The MSDN license agreement is detailed and worth reading in full. There's an excellent summary of your rights as a subscriber here. This paragraph is especially noteworthy:

Many MSDN subscribers use a computer for mixed use—both design, development, testing, and demonstration of your programs (the use allowed under the MSDN Subscription license) and some other use.  Using the software in any other way, such as for doing email, playing games, or editing a document is another use and is not covered by the MSDN Subscription license.  When this happens, the underlying operating system must also be licensed normally by purchasing a regular copy of Windows such as the one that came with a new OEM PC.

If you're a professional developer or designer who uses Microsoft products, MSDN subscriptions can be a bargain. If you just want cheap access to Windows 7, you have better options.