Transition to Linux

If you are planning to buy a new computer:

I suggest you to check the specs of the machine and google for the corresponding drivers.
Running Linux becomes a lot easier if the vendors have released drivers in the open source market.
Proprietary drivers, especially for video cards are a pain  and often have some compatibility issues.
ATI is infamous for their reluctance to release the drivers on open source.
Running your machine with the wrong drivers can cause a lot of chaos and especially when it comes to graphic cards.
From personal experience ATI graphic cards have some heating issues with Linux and the problems are usually hard to diagnose.

Preparing Your Computer For Installation

If your current operating system has used up all the space on your hard drive (used up implies the the file system uses the entire drive) then you'll have to shrink a volume.
Windows 7 comes with a memory management tool. Hit WindowsKey+R and type compmgmtlauncher . Select storage . Here you can view the layout in which the drive has been partitioned.
Right click on a partition and select shrink.
Follow the instructions on screen and create some space.
Note that only 4 primary partitions are allowed, logical partitions can be many, so if you already have 4 primary , you'll have to backup the data and delete one.
You do not need to format the newly created partition. We'll do this while installing Linux.

Installing the Linux Operating System

The open source community has made the installation procedure far easier that it was before. 

Download your favourite distribution

Here I've advertised a few of them 

Ubuntu: Maximum user base, extensive help forums, easy to learn

Debian: Offers much more control, harder to master, updates last longer

Fedora: For geeks,frequent updates great for development, spin off from redhat

Mint: Great looks, good for beginners

Arch : Build your own linux from scratch. Steep learning curve

Check out 5 Flavours of Linux for more information

I recommend you pick any of the first 3.

Once you have downloaded the image, Install it on a flash drive, there are some free software that allow you to do this., Download Universal USB installer.  Find an empty flash drive and install it there

Plug in the flash drive and reboot your system.

If your computer does not boot from the flash drive go to the boot menu and change boot device order. The USB should come first.

Once you boot into the new operating system, installation is as easy as following the instructions on screen. 

The only place where you have to exercise caution is when you select the drive where you wish to install the OS. In the partition manager (one of the steps of installation) Select custom layout. 

Remember that you have to allocate a partition for / (the system root) the rest are not mandatory. Although, I do recommend you to allocate space for swap as this comes in handy when you i) don't have enough RAM ii) for hibernation.

But then again you can also create a swap file, without creating a new partition, after installation . The choice is up to you .

The precise steps for installation will vary slightly  depending on the distribution.

Once everything is done, you computer will boot into the GRUB menu. Select the operating system. 

Congratulations, you are now officially a geek!