Old customers vs New customers. how to check that?? Help

I want to check 2 scenarios

1) I want to compare sales for the customers with less than 1 year old vs clients for more than 1 year old in a period of time X.

2) I want to compare total sales for the clients converted teh LAST YEAR vs the Customers converted THIS YEAR in a period of time X.

I have Converted Date of the customers. Just I don know to performance a Measure our a Running(by time) Column.

Thanks,