While we had to be content with big washes of synth strings in the old days (think of Gary Wright's "Dream Weaver"), times have changed. String section samples are now often broken down into violin, viola, cello and double bass sections. While these do sound a whole lot more authentic, just grabbing a handful of notes won't truly sound like real strings. Here's a better way: Record each string part individually. In a real orchestra. the first violins may be playing one note, while the second violins are playing another. Same with the other sections. If you just play chords with your right hand, you're actually playing far too many notes. Most string section samples may have as many as 24 violins, so if you play three- or four-note chords, it sounds like 72 or even 96 violins. No orchestra has that many. Also, not all strings would necessarily be playing at the same time and with the same technique. Your first violin section might play legato, while the cellos might play staccato and so forth. In the "old days" (you know, the 1990s) we had a modest number of tracks available. Today, particularly when recording to a computer-based application like Pro Tools or Digital Performer, it's not uncommon to have 24, 32 or even more tracks, depending upon the computer's CPU. These techniques also work well for winds and brass, as well. Give them a try and you'll end up with a better, more realistic orchestral arrangement.