I saw on the I-751 instructions that you need to submit 2 FD-258 fingerprint cards.

Am I getting it right here; I have to go to a USCIS office, get fingerprinted, submit them with the paperwork, and then go and get fingerprinted AGAIN when the notice arrives in the mail???

I hope somone can help me with this.

Unless you are in the Military or work for the Government overseas.... then NO

http://www.uscis.gov/files/form/I-751instr.pdf

Exception:
Those who reside overseas pursuant to military or government orders, including conditional resident dependents residing overseas and listed under Part 5 of the form, must submit the following items with Form I-751:

1. Two passport-style photos for applicants and dependents, regardless of age.

2. Two completed fingerprint cards (Form FD-258) for applicants and dependents between the ages of 14 and 79. You must indicate your Alien Registration Number (A#) on the fingerprint card and ensure that the completed cards are not bent, folded, or creased. The fingerprint cards must be prepared by a U.S. Embassy or U.S. Consulate, USCIS Office, or U.S. Military Installation.

Kez

Sorry, read the forms a little to fast, thanks for the reply!