What we have done for a number of clients is the following:
Create a sql database with a tabel which stores your products.
Create a DTS package which opens the products and places them in the
Next the dts package start a executable.
This executable connects to the database and picks up all products and
uploads them to MSCRM. This is a program which can be created using the SDK.
Doesn't take long and a lot of validations can be done by using SQL DTS and