think this is the belt driven off the camshaft which drives the p.a.s pump and water pump,it would be advisable to have a good look at the spring loaded adjuster pulley which the bearings sometimes break up,it is a while since I done one and can`t remember it being too difficult,remove the top cover and a small socket set and spanners done the job,you can get belts and adjusters at motor factors which could save you a bit also,good luck
cdc
July 2012