colour change at end point

end point is the point that we recognized the reaction is completed
but remember
this is not the equivalent point.
(eq. pt. is the point that the reaction is just completed
In your cast
both indicator can be used

Why is it so?
pH value drops quickly when the reaction completed
(NaOH at conical flask
the curve is something like...
pH
^
l－－－
l　　　│
l　　　│
l　　　　－－－
----------------------------------->Volume
after the reaction completed
the pH will continue to drop

pHa(phenolphthalein change colour)
pHb(eq. pt.)
pHc(methyl orange change colour)
pHa -a few drops of titrand> pHb -a few drops of titrand> pHc

this shows that methyl orange and phenolphthalein are available
besides, you should know that
at end pt. the solution no longer neutral
but it is ok

easier method:
if the reaction has...
strong acid: methyl orange ok
strong alkali: phenolphthalein ok
both: both ok
neither : both x ok

hope can help you~

2012-03-26 19:36:42 補充：
never mind
but you need to know the colour change
if you use phenolphthalein
while strong alkali in conical
colour change will be from purple to colourless
on the other hand
phenolphthalein when strong acid in conical
=> from colourless to purple

be careful for the "from .... to ..."

Actually, both methyl orange and phenolphthalein can be used in this case

although the end point of phenolphthalein(10) and methyl orange(4.4) does not seem close to the equivalence point(7), the difference between 10 and 7 is actually very very small, even a drop of acid may change the solution sharply from pH 10 to pH 7, this is also the same for the methyl orange case

有圖為證
http://www.chemguide.co.uk/physical/acidbaseeqia/indicators.html#top