<p>May 1, 2002 -- WASHINGTON - Saudi Arabia has hired a slew of D.C.'s most powerful lobbying and p.r. firms - including turning to an ad-buying company that's helped top Republicans - to buff its post-9/11 image, The Post has learned. One firm, Sandler-Innocenzi, which has worked for the Republican National Committee, recently was used by the Saudis to place TV spots portraying the kingdom as an ally against terrorism, according to the group that won the contract.</p>