If your sure it's the charger/power lead then the usual problem is at the plug that goes into the laptop (being a thin cable, it strains the wire if you frequently use laptop while on charge). Try pushing lead into end of plug while plugged into laptop(hold plug while doing this so as not to strain socket in laptop) if it works you have two options, buy replacement DC power plug, cut lead back, make sure wires are on right way round and solder it on (less than a pound from Maplins, but you need to know size) or replace charger (universal ones available on eBay for around £12 delivered)
Ian
November 2006