You don't normally purchase a car sight unseen, so why migrate from Windows to Ubuntu without getting a feel for what is under the hood?
To that end, Canonical produces a Live CD version of Ubuntu (also the other Ubuntu flavors) that allows you to boot and run Ubuntu from a CD. The Live CD is a full Ubuntu version which allows you to install software, alter your Desktop themes, create various Desktop (X)Windows and so on. In other words look Ubuntu over before you decide if it is right for you.
The only limitations to using the Live CD is the amount of memory you have in your machine. The memory limitation is imposed because the Live CD uses your memory as a hard drive and system memory at the same time.
The Live CD also has a feature that allows you to save system and configuration files to an ISO thumb drive so that you can start the Live CD up at a later date and automatically apply the saved configuration changes you made in your previous Live session(s).
You can also use the Live CD to install Ubuntu once you decide that you want to migrate to Ubuntu or use it as an alternate OS.