Here in central Connecticut our oil-fired, steam boiler has been estimated at 35 - 40 years old. They think it was the first non wood-burning furnace installed in our 89 year old house. The steam rattles through 12 cast iron radiators and burns though about $4,500 in oil every year, plus another $1,200 in parts and labor for service calls (usually emergency weekend/ holiday calls).
All that said we currently have no heat, a better stretch then last week to be heat-less for sure. We are investing in a new gas furnace that will circulate hot water through our 12 cast iron radiators. The system is just short of high-efficiency because even with the extra rebates for the HE system our HVAC guys - we chose a multi-million dollar company that was close in price to everybody else - said we were going to see so much of a savings already that a high-efficiency furnace wouldn't add enough additional savings to pay for itself over a reasonable period. The whole thing including taking out the 275 gallon oil tank from the basement came in at just over $10k. So if we save 30% or so the whole thing will pay for itself over 6-7 years. All-in-all not bad, I think, to no longer have to worry about waking up to no heat.
The system will actually monitor the inside and outside air temp and power the furnace based on actual needs, which we thought was pretty cool.
The down sides are no more reassuring clanging of the pipes, and they tell me the basement won't be as warm when the new guy is on. Without telling Mrs. RC I'm getting a quote to add two water radiators down in the basement.

old

new
But for today it is 38 outside and 51 inside.

Just thought I'd share.