Order by value in dictionary

[Abandoned]

Hi..
I have a dictionary like these:
a={'a': '1000', 'b': '18000', 'c':'40', 'd': '600'} ...... 100.000
element
I want to sort this by value and i want to first 100 element..
Result must be:
[b, a, d, c .....] ( first 100 element)

I done this using FOR and ITERATOR but it tooks 1 second and this is
very big time to my project.
I want to learn the fastest method..

I'm sorry my bad english.
Please help me.
King regards..