Ditto Bills comments. If the wire is OK still, the most likely failure points are the swages and other connection hardware. Here's a great exposition on what to look for:
http://www.dixielandmarine.com/yachts/DLrigprob.html
Personally, before spending my $$ on a new
rig for something to be weekend sailed...I'd want to see some evidence of the deterioration from the rigger and not just an "it's old and needs to be replaced".
Having said that, we replaced the entire
rig on both of our last 2 boats in the interest of peace of mind while at sea...so I guess it kind of depends on what is found and how you intend to sail the boat. BTW...If you do replace the
rig, consider the mechanical terminals rather than swages. (Like Norseman,Staylock etc.)