Timing belts can go out without any warning whatsoever.  And if it
happens while you are on the freeway, or even if just cruising the
streets, it can mean disaster.  It basically freezes the valves in
whatever position they happen to be in when the break occurs.  And
although the valves freeze, the pistons do not for several revolutions
of the motor.

The result is pistons reaching the top end of their travel in the
cylinder, finding exhaust or intake valves in the full open position
and promptly smashing them into warped little chunks of useless metal.
At the same time, the piston doesn't take the battering too well
either and can suffer greatly.

But the fun isn't over yet.  All that broken, twisted and red hot metal
you have just created is now free to get jammed against the cylinder
walls making cool little gouges and scrapes which just about puts the
icing on the cake.  Your fantastic new/used car is now a very awesome
paper-weight, unless you have several thousand dollars more to buy and
install a new motor.

Just a graphic explanation to let you know the importance of having it
done asap.  Of course, I didn't change mine until the 75k mark, but I
was uneasy about it from 60k on.

Raja,

low mileage has nothing to do with low coolant or more water.

I have an 01 spyder v6, it's a gas guzzler, especially since it hauls butt!
I average 20mpg around town with freeway.
The timing belt should be replaced 75k on average.  timing belts can easily
last 90k, but since the engine is an interference engine, it should be
replaced at a decent interval, 75k is safe.

the 60k checkup from the dealership is a joke and should be pretty much
ignored.  You can visually check 70% of the car by looking at it.
the rest is easy fluid changing, oil, tranny (the spyder has no tranny
filter, just drain atf and add more). and check the CV axles.  Not to big of
a deal.
the timing belt job yes should have the water pump replaced as well and also
the tensioner pullys.