It's the same as any other OS install, the installer is as complicated or as automated as you want/need it to be, however I recommend pulling your Windows HDD and replacing it with another hard drive to install Ubuntu onto just in case Linux isn't for you.
Also, bear in mind that you don't have to be restricted to vanilla Ubuntu. There's a number of Ubuntu flavours that are every bit as good as vanilla Ubuntu.
To avoid potential headaches, remove devices like webcams, external drives, printers. Nothing wrong with leaving them in, though. It increases your chances, is all.
If you won't be able to boot the installer, you're gonna have to toggle "secure boot" related things in the CMOS (BIOS) to "legacy". Make sure you're not booting into an UEFI instance of a boot device. Avoid UEFI in general.
You might have to set your hard drive controller from AHCI mode to Legacy IDE if your hard drive is not recognized by the installer.
I recommend installing from an optical disk so you can hear it "going" - you'll know if it stopped dead.
The installer will detect your existing Windows install and add a boot loader to enable choosing the OS after POST, but it's better to follow Bullet's suggestion on disconnecting your main drive just in case.
Personally I've tested Mint recently and it was okay to go for newbies (no offence).
Very good points michalrz! I tend to agree that Linux Mint is quite simply a fantastic distro for anyone thinking of switching to Linux from Windows.
One thing to keep in mind though, and this is very important and may mean the difference in success or failure when it comes to shifting away from Windows - Always remember, Linux is not Windows and there's no prerequisite that even suggests that Linux should mimic the behaviour of Windows, there may be a number of things you need to unlearn. If you accept this and really try, Linux may very well become a new level of freedom in relation to using your PC with very little in the way of sacrifices.
3. Boot from your USB drive. It'll boot straight to the desktop and you can try the OS out. When you're ready to install just click the desktop icon for the installer and it'll walk you through the process. It'll give you the option to wipe the drive or install alongside Windows.