I used to use these tools to develop my applications, I strongly recommend:

Microsoft Visual Studio .NET
is a powerful IDE to develop easily desktop and web application. I use C# and VB as language and also is easy to work with database.
Full Versions:
Express Edition(FREE):

Visual Studio Extensions
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Microsoft Expression
provide a bunches of products for the graphics and media world. I’m using Microsoft Expression Web that is like Dreamweaver focused to ASP .net technology.
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excellent image manipulation program. It is like Photoshop but FREE software (GNU) that was created initially for be used in Linux.
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Foxit Reader
is not really a developer tool but is used to read PDF files. The main reason I chose it instead of Adobe Acrobat it is liter and faster. Foxit also provide PDF editor that is cheap compared to others. I recommend also the virtual printer PDF995 that is FREE to convert any file (doc, html, xls, etc…) to PDF.
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 The Fiddler web sniffer software is one of several well-known HTTP debugging proxies. It works well, and the proxy nature of the sniffer makes it stand out among other web sniffing tools. Ideal for: HTTP/HTTPS Traffic Recording, Web Session Manipulation, Web Debugging, Security Testing, Performance Testing
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