Italian and Spanish are more alike. Spanish cannot be understood if you know French. I have been studying French for 6 years and when I was in Miami in a hotel, I couldn't understand the cleaning lady. Although another girl who claims she knows French (which I doubt) said she could understand it (which I also doubt).

Portugese is similar to Spanish. If you know Portugese, it's easier to understand Spanish than the other way around. If you know Spanish, you can understand Portugese, but it's a little harder. I know this because my friend's father, who's fluent in Spanish because he's from Panama went to Portugese one time and told me he could understand them, but needed them to speak slowly so he could understand. To conduct business, he spoke Spanish and they spoke Portugese. So it's obviously possible.