Turn your head and cough

I had my annual home inspection this week.  Heating/AC, plumbing – the works.  Turns out I need a new furnace desperately (much more than I need a new water heater).

I also need new ductwork.  Yeah – sounds expensive.  But I know it’ll save me in the long run, and I know a new furnace will be a lot safer than the dinosaur I have in the attic right now.

Any of you have any experience replacing a heating system lately?  Any recommendations?