A word of caution when replacing these batteries willymagic, do not to use your fingers when placing the new battery in its slot. The grease from your fingers can damage the battery and may not give the life expectancy you would normally expect. I would recommend that you use a pair of tweezers from taking the new battery out of it's casing, to inserting it into your motherboard.
many thanks guys i will deffinitely use PLASTIC tweezers then, can anyone tell me where i could go to get one of these batteries?.. i mean are they standard or does each motherboard use different types?.. many thanks