well you could try searching for a soundfont with a harp in it, or search for sample cd's with harps.
and if you want to make it more electro you can place effects on it.
http://www.youtube.com/watch?v=ixL_jmGRDXY
The harp samples are taken from Future Music magazine number1 or 2 cover disc. So are the breaks n bass come to think of it.
Linplug do a fantastic vsti called Saxlab2 it might be worth while checking out their website, if not, I'm sure there are plenty of other vsti's out there.
Or are you talking about the arpeggio? (arp)