Hey Parnold,
If you just plan on riding this bike on the street around neighborhood, you'll be losing a lot of energy with the full suspension as it was designed for the rough terrain of mountain biking. It sounds like you have some good garage and estate sales in your area, so if you ever come across an even older mountain bike (early to late 80's) for 15 bucks and in good shape - buy it too!
As I said in my previous post, those bikes are made from all chromoly steel (usually 4130 which is the holy grail) and have no shocks. You will be amazed how comfortable the ride is (even without shocks) because of the frame material. And you will be much more efficient with your power transfer to the bike.
Or if you really like the bike pictured, you can swap out your front shock for a rigid fork. Most of the time those old front shocks are no good anyway. Just be sure the rake is the same. I bought a chromoly rigid fork from Bike Nashbar for $49 when I converted my Gary Fisher Tassajara to a utility bike. (Obviously you get more bang for your buck with garage sales or even better - trashed bikes.)
I would also change out the knobby tires to a commuter tire. Much more road friendly.
Scott