Everyone knows Microsoft for its Windows OS and Office productivity suite. But the software giant makes plenty of other apps, many of which are entirely free to download and use. In fact, there's a ton of them.

When we started counting up all the best free Microsoft apps, we thought we'd find 20 or 30. In the end, we found a lot more. And because this is Microsoft, these apps aren't just okay, they're good. Great, even.

There's a free program or service for just about every aspect of PC use, from headline-grabbers such as Windows Essentials and Microsoft Office Web Apps, to smaller but no less useful tools such as Microsoft Autoruns, Security Essentials and Desktops.

It's not just about work, either; Microsoft is responsible for lots of apps that are enjoyable and fun to use. See through the eyes of the world's telescopes, play a game or two or - better still - create your own with Kodu Game Lab. The list just keeps on growing.

Some of the programs here are unfinished, and clearly marked as such. That means there's a chance you may run into problems using them - nothing major, but take a System Restore point before you proceed, just in case.

We also recommend you don't attempt to install every program in this list in one go; you'll quickly bring your computer to its knees. Instead, pick out tools that excite you and give them a try.

With the Windows Essentials apps, you can choose the ones you want when you download the Windows Essentials installer program. So, what are you waiting for? You're about to make your PC more efficient, secure and fun without spending a thing.

1. Microsoft Office Web Apps

Download 1. Microsoft Office Web Apps

This must be one of the company's biggest giveaways; you can now gain access to the core features of Office Word, Excel, PowerPoint and OneNote for free through your web browser.

Just log on with your Windows Live ID to create new documents or upload existing ones from your computer to your Windows Live SkyDrive account, then edit them in your browser window. Even if you already own a copy of Microsoft Office, this useful freebie enables you to access your documents from any web-connected computer.

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2. Windows Live Mail

Download 2. Windows Live Mail

It's simply the best free email tool there is - essential for Windows 7 users, and a step up from both Microsoft Outlook Express and Windows Mail, too. Reasons to upgrade? It works brilliantly with multiple email accounts, gives you offline access to web-based providers such as Hotmail and Gmail and organizes your mail intelligently into conversations.

Windows Live Mail
Get offline access to web-based email providers

It also integrates cleverly with a built-in calendar, enabling you to organize your life, too. Windows 7 and Windows Vista users can also enjoy the new photo email option, which enables you to share dozens of pictures without clogging up other people's inboxes.

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3. Microsoft Mouse and Keyboard Center

Download 3. Microsoft Mouse and Keyboard Center

Microsoft's attempt to move us all over to a new touch-based Windows interface hasn't gone as smoothly as it hoped. Most of us remain perfectly happy using the traditional keyboard and mouse to find our way around. And, if you've bought Microsoft's own input devices, you'll want this free download, which combines the functionality of Intellipoint and Intellimouse into a single app, enabling you customize how your mouse and keyboard will behave in Windows 8 and 8.1.

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4. Visual Studio 2013

Download 4. Visual Studio 2013

This freebie will appeal to developers, giving you all the tools you need to build apps and desktop programs without charging you a penny for the privilege. It comes in three flavors: Web for web-based apps and services, Windows for Windows 8 Store apps, and Desktop for those wishing to build traditional desktop apps based on C#, Visual BASIC and C++. Note you'll need to sign into Visual Studio within 30 days of installation to register and sync your settings - all for free.