Can anyone advise me on my legal rights regarding eviction?

I may be jumping the gun here, but I want to be mentally prepared for the worst.

I live in California, in Contra Costa County, specifically. I live in a single family home with my cousin, who personally has no issue with my living here. However, I have a messed up family with one or two members in particular who have decided to meddle in my life and seem to want me out of this house.

As far as I know, my great-uncle owns the property, which he has given to his son (my cousin) to live in. As I said, my cousin is fine with my being here. My cousin’s sister has nothing better to do and seems to be trying to get me out.

I’ve lived here a year and 8 months. I have no utilities in my name, since it’s not my home, but I do give my cousin money for utilities. I have not signed a lease, either. The only proof that this has been my address is my car registration, starting in March of 2010.

What I need to know is this.. can they legally evict me without notice? If they have to give notice, would it be 30 or 60 days? Do I have any sort of legal legs to stand on here, or am I just screwed?