If you want to experiment Ubuntu, you have also the option of using a virtual machine rather than creating a new partition for Ubuntu, this way you can test without much trouble. I am a Kubuntu user, I prefer Kubuntu over Windows 7 a thousand times.
It is much safer, specially because you usually won’t just download an installer of a random program from some random page on the Internet, but instead you’ll download from the repositories maintained by Canonical (the Company behind Ubuntu) and volunteers. It is much less likely to install malware that way, that is why Linux viruses have a hard time spreading themselves.
Contrary to what people usually say, you don’t need to use the terminal, the terminal is actually a bonus. You can do many things from the terminal you won’t do easily without it, either in Windows or in Linux. But you can live without it most of the times. It is much easier to do complex things using a terminal. For instance, telling the computer to shut down after one hour or do a sequence of commands (e.g. update your system, download a program and shut down) while you are e.g. at lunch is very easy if you know basic terminal stuff.
You won’t need to defragment your HD, and you will get less damage to your data in the case of a blackout because of the journaling system of the partitions. Manipulations on the hard drive archives also seems to be a lot faster than in Windows. Sometimes in Windows 7 you have to wait a while until it starts to copy a file or when a program asks for administrative rights, which is very annoying, at least to me.
If you intend to learn programming, you should really try Linux.
OpenOffice is very good, you won’t miss Microsoft Office.
Anyway, all I know is that I can’t live with Windows 7, it annoys more than helps me. I use it just for gaming, and for some time using Wine I survived for a long time without any Windows in my machine at all. My Windows installation is actually very simple, with all Windows features deactivated, a Firefox and games. Everything else I do in my Kubuntu: most of my Internet browsing, listening to music, watching movies, torrent, instant messenger, programming, using tex… Kubuntu also helped me a lot when I changed my hard disc two days ago - I couldn’t count on Windows very much for that.