Overture vs Wordtracker? Conflicting results please comment.

[Macbeth]

I seem to get conflicting data between the tool keyword tools and i don't which one to take seriously.
For example on the word seduction per se you get 15000 searches performed in Dec 2004 (according to overture), yet in

Wordtracker it says 1100 searches on that word alone in the past 60 days!? Which is nowhere near the overture figure even when accounting for the differences in broad match.

Can anybody make any sense of this?
In any case which tool can be better relied upon for the prupose of knowing the number of searches for the keyword in a month?

Does anybody have any better alternatives?