There are several options for support depending on your need:

Microsoft products
If you need help with installing, uninstalling or using any Microsoft product, please contact Microsoft support at http://support.microsoft.com/. For assistance with products purchased from Microsoft via Windows Marketplace, please contact Microsoft Store support here: http://store.microsoft.com/help/Contact-Us

Third party products
Microsoft no longer supports downloading of third party products previously on Windows Marketplace. Please contact your merchant of record for more information on how to access these products.

The digital locker service will remain operational through August of 2009: During this time we will send emails and web communications to help customers transition from digital locker. By the end of August 2009, digital locker service will be shut down. Digital locker account holders should retrieve and record elsewhere their software keys from digital locker before this shutdown occurs.

How do I find more information on digital locker?
See the digital locker FAQ

Link to Japanese localized version
Click here

For purchases made on Windows Marketplace:
Each seller listed on Windows Marketplace has its own return and refund policy. Please contact the product manufacture or seller of your purchase.

For purchases from Microsoft Store:
For more information on Microsoft Store returns policies, please click here http://store.microsoft.com/Help/Returns-Refunds.

There are many options for partners to showcase their products across the Microsoft network (go to http://www.microsoft.com/windows/compatibility/windows-7/partner to find more information).

You can purchase Windows software and Microsoft hardware online at Microsoft Store by clicking here: http://store.microsoft.com

It's an online store where you can purchase a full range of Microsoft products directly from Microsoft. Many software products on the Store can be purchased and downloaded immediately.

If your purchase was made from Windows Marketplace and involves the installation, removal or use of your product, please contact the manufacturer. For Windows Vista, go to the Microsoft Help and Support Web site.

Please contact your Merchant of Record (aka "MOR") to determine if a refund is available.

Microsoft will destroy any personal information on the associated data server, in compliance with our standard policies. Microsoft respects your privacy. Please read our online Privacy Statement.

Your BitLocker and EFS recovery keys will no longer be available once the Digital Locker is closed. It is very important to maintain a copy of your recovery keys for BitLocker and/or EFS. You should print a copy of your BitLocker recovery password and store it in a safe place. Similarly, you should save a copy of your EFS recovery key on a data store separate from your computer.

Microsoft will destroy any recovery information on the associated data server, in compliance with our standard policies. Microsoft respects your privacy. Please read our online Privacy Statement.