vbgagnon said:
I've got an older Jamis Cross Country, ..but want to get back into riding.
An old MTB is a good choice for that, it can be roadied up quite nicely and the fairly upright riding position is good both for comfort and for keeping your eyes on surrounding traffic. And if exercise is your main goal then you can't beating the economy in riding a bike you already own.
vbgagnon said:
The main reason I want to get back into cycling is to get back into shape, I've tried running but my shins just cannot take the pounding of running anymore.
Just because biking is low impact doesn't mean it can't be harmful. Do your warm-up, your wind-down and your stretches. Keep the cadence up (a bike computer can help you with that) and be wary of the high gears. Don't make riding your only form of exercise, but add some other discipline too to make it a well rounded program.
vbgagnon said:
So I guess my questions would be pretty basic. How do I setup to get a comfy ride of my bike,
You've already received some advice on basic bike fitting and you can find more on the web. Be prepared to buy some stuff.
If you haven't ridden in a while odds are that any saddle you try is likely to be uncomfortable initially, but if it's still uncomfortable after a few weeks of regular riding (and at few different angles) then it's time to start looking for a new one.
A good saddle is one that fits you, and there's no direct link between fit and price.
You might want to replace the stem at some point to get the handle bar in a better position.
Your current cassette probably has a far greater span of ratios than you're actually using, so you might consider a road cassette instead. As long as you still have the granny gear available in front you probably won't miss losing the biggest sprockets in the rear.
Get some real bicycle pants, and use them as intended. Once you've found a size/make that fits, buy several pairs so that you always have some freshly laundered.
Get some bike shoes and spd-style pedals.
If you already have windproof/semi-waterproof jackets bought for running they'll do nicely for your riding as well.
Fenders are nice if the weather turns bad. I particularly recommend a rear fender to protect from the rooster tail of road crud you otherwise will project onto your back.
I'd also suggest a helmet. It might not save you from "death by SUV", but it can protect you in a lot of less dramatic injuries. Particularly during the embarrassing slow sideways topple experienced by most people coming to terms with spd-pedals a helmet looks really likely to come in handy.