2007W is the same as 2007W first strike. THere was an earlier thread this evening about what the difference was between first strike and one that is not and whether there was any additional value to a first strike issue. Basically the first strike or early strike designation was a project by third party grading companies to offer something else to collectors with the smoke screen that it would be worth more if it was stamped first strike. There is no additional value to a coin whether or not it was stamped first strike or not, but I am sure there are collectors out there who have really bought into the whole idea and would be willing to pay more for the coin. But to answer your question when using the PCGS pop report, I would guess that all MS 70s - whether they are first strike or not - are all lumped together. I may be wrong.
In this link to the thread I mentioned, there are several other links to both PCGS and NGC definitions of first/early strike coins and the US mint's response to first strike coins. Good luck. http://www.cointalk.com/forum/t45774/
PS - welcome to Coin Talk. If you have any questions please ask, the group here is very friendly and informative.
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"These are the times that try men's' souls. The summer soldier and the sunshine patriot will, in this crisis, shrink from the service of their country; but he that stands it now, deserves the love and thanks of man and woman. Tyranny, like hell, is not easily conquered; yet we have this consolation with us, that the harder the conflict, the more glorious the triumph."
Thomas Paine, Intro to the The Crisis, December 19, 1776 | 
