Best bike for a new rider?

When I get my tax return, I'd really like to use part of it to buy myself a bike and a rack for the back of my car. I'm excited about this new form of exercise! But I don't know what kind would be best for me. I haven't ridden a bike since I was a kid. I mainly want to ride it on some of the bike trails and sidewalks near my house. Should I look into a mountain bike in case I want to do that at some point too?

I would recommend a comfort type hybrid or simple mountainbike.
When you have not ridden for a while the more comfort the better.
Padded seat,suspension seatpost,adjustable handlebar stem,thick hand grips etc....
It my advice to try and make the experiance as easy as possible at first.You can always change your riding habits to accent your excercise level.

Good luck and keep pedaling
p.s. always wear a helmet and wear reflective gear at night as well use rear and front light or blinkers.

I agree with the other answers as well, but if you are considering going off road and onto a mountain bike trail I would get a mountain bike. From my standpoint a hybrid's best use is anywhere from a paved path to as extreme as about a dirt or gravel road. Doing more than that on a hybrid can be hard on the bike as it is not designed for that kind of abuse.

For the bike and the bike rack, your local bike shop can do a good job helping you out as well.
Whichever way you go- enjoy!

I would look at a hybrid. Bikes have come a long ways... Look for an all aluminum frame, a good drivetrain (Shimano Altus or higher). I'm personally not big on front suspensions, to me they are less efficient.

Checkout some of the Giant bikes, one of my favorites is the Sadona
http://www.giantbicycles.com

If you are looking for a great buy, take a look at the Forge M Street. These are more for street or all paved surfaces.
http://www.forgebikes.com/mstreetbk.asp

As for a car rack, if you plan on biking "a lot" get one on your roof. If just weekends, I would suggest one on back trunk. I found either your car dealer can assist in assuring the correct fit or a really good bike shop can help you. Either look at Thule, Yakima or for a trunk rack look at Saris.

Make sure you buy a Helmet!!! Have fun and enjoy.

well if you want to use it for trails,etc
i would go with a mountain bike because that's what mountain bikes are best for and also they have gears so u can make your exercise harder