First off, welcome to the boards.

Secondly, congratulations on quitting smoking. I've been there and your deidcation deserves some credit..its amazing how much better you'll feel and how much money you'll save It is probally the healthiest thing you could do.

When people ask what type of program to begin with it is hard to say because I don't think any routine will fit everyone perfectly, but I'll add some of my critiques and hopefully some of the others can chime in with their advice.

day1..chest, biceps...benchpress, peckdeck, then bicep curls.
- It seems as though your only doing one exercise for your arms here. I would suggest adding in some incline dumbell curls and maybe some preacher curls also. This should give you an evenly built arm structure.
For the chest you might want to consider adding in maybe one more exercise like incline press or incline dumbell presses to target the upper part of your chest since the bench will target the middle part. The peckdeck is good, but don't be afraid to use dumbells as they will help build up your stabilizer muscles which the machines don't hit.

Another suggestion, maybe just do chest on this day alone. This will allow you to go pretty heavy especially since you have a rest day right before this. Then you could do your biceps and add in the triceps on a seperate day so your just doing arms on a day then.

day2..back..pulldowns, then rowing.
- I think your going to need more than two exercises for your back if you want to hit everything and have a nice build. If you have a strong back you can add in some deadlifts to strengthen your lower back which will help your overall routines. If you toss in some pull ups (if you can do them) they will hit your lats and mid back. If you can't do them at first use a spotter machine or train well on your pulldowns as they will help you get better at pullups. The rows are good, just remember to keep good form.

day3/4 rest.
- Resting schedule is up to you, but you may want to squeeze some cardio in here if possible so your at least doing something on these days. Depends on how hectic your schedule is.

day5..shoulders..military press..dumbell press and lat extensions.
- Good. I do pretty much the same thing but add some shrugs in. Whatever you like.

day6..legs..squats..45 degree press and seated calf extensions.
- Good, maybe add some leg curls to hit the hamstrings.

day7 rest.

You forgot about the triceps! Make sure you add some tricep exercises somewhere into your schedule so you don't have unbalanced arms. Triceps are also very important as they help you on many exercises such as benchpress and so forth as secondary muscles. My favorite exercises for triceps are skullcrushers and close grip bench, going heavy on both. You can do whatever you want for them including kickbacks (or as I like to call them pure hell) and pushdowns. Just pick what your comfortable with and work your way up.

Like I said these are just suggestions and when your coming back to the gym after a long time away, getting comfortable with everything can suck until you find what your comfortable with after the initial shock. Have you looked into the 5x5 program? This is a great way to start off light and build a base while continually forcing your muscles to grow and adapt.

Also at 40 should I expect signifigantly less results than at 25?
- Well testerone production does slow down as your older, but some of the best looking guys at the gym are some of the older veterans who are dedicated. Stick with a good diet and get plenty of protein and you should see some good results.