You can load samples only by purchasing a SRX expansion board. You find them used, on Ebay their average price is still around 160 euros. But they have great samples. My favorites are:
SRX 04 Symphonique Strings
SRX06 Complete Orchestra (400 samples/sounds)
SRX07 Ultimate keys
SRX 09 World (400 samples/sounds)
SRX10 Big Brass

http://media.roland.com/en/IT/SRX_IT/index.html

BTW, these expansions are presently rereleased in the form of downloadable packages for the new Roland FA-06, and I assess them as the best part of the Integra soundset. Strings and brass are very realistic.