Hi Bernardo,
If you've installed these from Business Content, you should have also installed the MultiProvider that ties those 2 cubes together as well. The MP name is: 0PCCP_M30 ( Product Costing Analysis: Itemization ).
Essentially the difference between the standard InfoCube and the Virtual Provider is that the InfoCube will actually store data in your BW system whereas the VirtualProvider pulls the data in real time; pulls information at run-time of the query that hits your MultiProvider. So essentially when someone runs their query, it will pull historical data from the InfoCube but simultaneously pull data that you may not have through the VirtualProvider. So an end-user puts in a date value to look at some costing data from January 1st through "Today" (same date they're running the query). Since you may not have "today's" data in your InfoCube yet because you update nightly, the VP will then extract what you do not have in real time by pulling directly from your ECC system.
At least, this is how it was explained to me. You basically want to have both of them, rather than trying to feed your MultiProvider and subsequently your reports from just 1 of them.