I'm a salaried employee and plan on giving my 2 week notice. If I give my 2 week notice there is a chance they may ask me to leave immediately. Are they suppose to pay me those 2 weeks, or do I just sign up for unemployment benefits?

Your employer can choose to accept your notice immediately and does not have to pay you for that time. Whether you can collect unemployment for those two weeks depends on the unemployment rules and regs of your state.

Your employer is only required to pay you for time worked. Therefore, if you submit your two weeks notice and they ask you to leave immediately, you probably will not get paid for those last two weeks and your final paycheck will be pro-rated for the time you did work. If you do end up working the full two weeks, then the employer is required to pay you for those two weeks.