1. Work with data in a unified and integrated way.
• Be more productive by using a single approach to querying and manipulating data that’s integrated with the way you write code—in the programming language.
• Language-Integrated Query (line) lets you use a single model to query and transform XML, Microsoft® SQL Server TM, and object data, helping you focus on what you need the data to do rather than how you are going to access the data.
2. Work with user interface designers.
• Share user interface assets like design elements and controls with graphic designers that use Microsoft Expression®.
• Both Microsoft Expression Web (ASP.NET) and Microsoft Expression Blend TM (Windows Presentation Foundation) supported.
3. Employ the latest web user interface techniques.
• New support for Web server communication techniques for AJAX- or JSON-enabled Web sites.
• New ASP.NET controls allow for better page management and templates.
• RSS and REST natively supported by the Windows® Communications Foundation.
4. Build stunning applications for Windows Vista®.
• Build powerful Microsoft Windows-based applications that take advantage of Windows Forms and Windows Presentation Foundation to make your applications really stand out.
• Smart client application improvements improve deployment and disconnected scenarios.
5. Build higher-quality applications with integrated unit testing.
• Powerful unit testing tools are now integrated directly into Microsoft Visual Studio® 2008 Professional.

Download this pdf Top 10 Reasons to Upgrade to Visual Studio 2008 Professional Edition