Mars or AIDS?

I read somewhere that the cost of going to Mars may eventually total up to $170 billion which is nowhere close to the $12 billion the US President has stated will flow into NASA's coffers over the next 5 years to help finance the Mars dream. I don't want to knock the US government's spending on AIDS (supposedly $1 billion this year) but aren't there significant, higher priority problems on Earth that need tackling before one starts dabbling in interplanterary conquest?