InfoPath Dev

I have a form that has two drop down menu’s. Each menu is pulling A LOT of values from a SharePoint list or in some cases even a web service. I want to make it so that the values of drop down 2 don’t populate until a selection is made in drop down 1, in which case it filters the values in drop down 2 and populates drop down 2. This way, the form doesn’t take so long to load.

Does disabling the 2nd drop down through conditional formatting so that it's only enabled when a selection in the first drop down is made accomplish this?

Disabling the dropdown is not enough. You'll need to set up cascading dropdowns, which will filter the data before loading the second dropdown. For an example, please read this:

http://www.infopathdev.com/blogs/greg/archive/2005/07/06/Create-a-Cascading-List-from-a-Hierarchical-Data-Source.aspx

Note that InfoPath's default data connection to SharePoint will load all data into the secondary DOM, so the best you can do is limit what you display in the dropdown. The form will still contain the large amount of data. If you have a web service or a third party tool, you could perform the filtering on the server itself.

Good luck.