I am sorry if this has already been answered somewhere else on the forum.
I just moved from Italy to the US with an F-1 visa. My brother (who is a US citizen) helps me out with my tuition and gives me about $20,000 a year. I'd like to open up a savings account to put the money in. Do I need a SS for that? Will I have to declare taxes on the interest?
Thank you for your help.

With F-1 visa you can get SS number. You need SSN to open the bank account.

On F-1 you are nonresident. Bank interest in case of nonresidents in not taxable.
Your brother can provide you support that is pay for your tuition and other expenses.

But if he gives you more than $13,000 as a gift, then your brother must file the gift tax return.
He can give you up to $13,000 now and $13,000 in Jan 2010 without filing gift tax return.

Direct payment of tuition for a family member is NOT considered to be a gift by the IRS.

However, the other $20K would be subject to gift tax reporting, though no gift taxes themselves should be due.