Is the $1,500 tax credit available for each product? Can I get $1,500 for windows and another $1,500 for a new HVAC system? Can I get $1,500 in 2009 and another $1,500 in 2010?

Even if you purchase multiple products you can only get a maximum of $1,500 over the 2-year period (2009 & 2010). Basically you can spend up to $5,000 during this 2 year period on a single or multiple products, for your  principal residence that you own and live in, and get 30% or $1,500 (30% of $5,000 = $1,500) back as a tax credit. If you get the entire $1,500 credit in 2009, then you can’t get anything additional in 2010.