Here at core, I use several freeware/open source tools and resources to make my life easier, and best of all, they are all free to use... A line-up :

Sauce Reader

This is currently (according to my opinion) simply the best RSS-reader available.
It is simple and works as expected with support for ATOM/RSS/RSS2.
If you need to track a lot of websites for updates, this is one of the most time saving assets you can have at this moment.
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DasBlog

The blogging engine I am currently using (you are probably looking at it right now). Very versatile and easy to setup.
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Smart FTP

Simply the best FTP-client you can get
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AntiVir Personal Edition

Free Anti virus that works (even the updates)
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LavaSoft Ad-Aware Personal edition

Remove all trojans/dialers/unwanted stuff from your pc
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Picasa

Manage your photographs on your pc with a tool by google
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SharpDevelop

An open source .NET IDE (no ASP.NET)
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Visual C# Express Beta

A c# editor from Microsoft
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TestDriven.Net

Currently THE plug in for test driven development in .NET
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LUA

The best embeddable scripting language. I still have to embed it myself, but that is another story ...
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InnoSetup

Create installation packages easily.
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Werkzeug1

Demo tool for creating top of the notch graphical presentations. Quite complicated, but also very powerful. I need some more time to dive in to this...
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