I know if you are syncing with a Mac and using Contacts all you have to do is edit the contact and check the box that says Company. That will list the company first and the contact name second. Sorry not much help if you are using windows.
I backed into another way to do it on the phone. By accident I found that if you enter the name of the Company first for a new contact, save that, close out the new contact. Then reopen the contact and add the persons name. The contact will then sort by company rather than name.
Conversely if you want it to sort by name, enter the name first and then the compan.
it did NOT work by simply entering the company name first, then going directly to the name. For whatever reason i had to completely save the contact as Company name only then come back and add the name.
Come to think of it, I ahve not checked as to what happens to that contact when it comes back into Address Book.