Here are the specs...
Scroll down and see the Xubuntu details.
I'd copy/backup any data first!
Ubuntu uses a different format for partitions, so you can't use the existing partitions. The install process offers you a wizard to deal with it, (as I recall... it was a while ago I did it!)
I'm not expert enough, (or at all with Linux!), to offere detailed instructions, but what you need to do rather depends on whether you are planning on keeping the Windows installation and dual booting, or replacing Windows?
Good luck! I'm sure others more knowledgeable with be along with more/better advice soon!