You should be very worried about the life left in this belt. Replaced mine at 160,000 Km and it was shot. Just posted that message to the forum yesterday.
As far as replacing it goes, unless you're a pretty good mechanic, don't try to do it yourself. Too much grief involved with removing radiators, hoses, main crank pulley nut, etc etc. It goes on and on. I've done it, I know. Give it over to a trusted shop. It'll cost you though. Lots of labour getting at it all.