Convert getdate to week and day of week

I have a query that run every day to update a summary table which has week number and day of week. what I currently do is delete all records from the summary table and then summarize all the data availabe from four tables adn then populate the table daily. I want to know if I can run the update query to run only for the week number and day of week depending on getdate. Can I do this?

Please help..Look up the DATEPART() function.