It's possible, but not advised, if you think you'll need to run Windows.
For example you may not find a printer driver for Linux and will need to reboot to Windows to print. There is very likely some reason you will want your Windows install back at some point.
Better to move your data to your C:/drive and delete one of those data partitions. Then you'll need to manually make multiple partitions where you deleted the one.
Typically Ubuntu (and all Linux) needs at least two or three partitions, at a minimum I mount / on one partition, /home on another, and use a third for swap.
1 -- Read this page thoroughly until you understand it, it's the page about installing Ubuntu in its own partition.
If you decide to go ahead and install Ubuntu in its own partition you will have a good idea of what to expect based on the link above.
Make sure you understand the part about Master Boot Record and Boot Manager. Not understanding MBR vs. Grub2 will cause a lot of potential headaches that can be avoided by using the Wubi install in the next link. If you want to be unable to boot your computer, messing with boot partitions without a full understanding is a sure ticket!
To install Ubuntu in your Windows partition, please review this page about Wubi.
2 -- Have a backup of Windows and know how to restore it
3 -- Look at this question (which your in a way duplicates) and make the final decision if you want Wubi or if you are ready to mess with repartitioning. You can test out Wubi now, then later when you are confident you really want to dump Windows, and you understand partitioning better you can try a repartition. You can also attempt to shrink your Windows C:/ partition to keep it and make space for Linux.
If you install the right packages in Linux you can see your NTFS drives, so a basic Linux install can easily live on 50-100Gb.
Summary: I suggest you install Ubuntu in the Windows partition first (Wubi link). Booting a "live file system" off a USB stick or CD gets annoyingly slow after a while. Until you really know what you are doing don't delete partitions. It's easy to cause a problem where you can't boot and don't know how to fix it.
I am sure you understand, formatting C:/Windows will delete your Windows installation. Think of the least harmful approach while you are still getting to know Linux.