If you are using Telelogic DOORS for your requirements, please have a look at the new integration with Visual Studio Team Foundation Server.
Microsoft® Visual Studio® Team Foundation Server Integration
This Telelogic DOORS integration, for use with Microsoft Team Foundation Server, helps development teams using Visual Studio tools to create and maintain traceability between requirements in DOORS and work items in Team Foundation Server via simple drag-and-drop. Now, development teams using Team Foundation Server can improve their requirements process using DOORS and its support for traceability into the Microsoft development environment.
This is a good news and another proof that if you need to go further the Microsoft solutions for a specific functional scenario (like the requirements with DOORS), Team Foundation Server will stay your centralized solution.
more information on : http://www.telelogic.com/corp/company/news/index.cfm