Air Conditioning

So...the summer cometh. Yay! Except, nay! We have no air conditioning, and lemme tell you--while I love our little window unit, it only cools the living room and the dining room, and every time I try to vacuum it blows the fuses, and...well, yeah. It's not quite adequate, although we can definitely live through many more summers if we have to.

But, you all know how noble Bradley is, how concerned he is about the economy. He really wants to do his part to stimulate economic growth in the country, and so we are considering installing central air. Only for the well being of the economy, of course.

And here's the other thing: our furnace is 14 years old, and furnaces of this type are usually good for 15-20 years max. So it may conk out next winter, or it might last another six years. Nobody knows.

So here's the dilemma: Should we replace the furnace with a furnace/air conditioning, because there are a TON of rebates/tax credits/etc available right now, and we would save $3300? (Bringing the price down to a measly (HA!) $7700.) Or should we just take the risk that the current furnace is going to be just fine, and just buy the a/c (without the rebates/credits/etc), which will be around $3200-3400?

Anybody have any advice/information? We wanted to tap into the great wealth of knowledge that resides in our family...so, speak up if you have any ideas!