Will I lose "stuff"?

Hi got an old IBM Thinkpad 600x which works absolutely fine and the only problem i have is the CMOS battery is on it's last legs ! Usual thing "error" 163 reset time date etc. I have ordered a new battery, which is compatible with OEM,i.e: comes in a nifty little package with 2 cables attached and a little plug.

Now although familiar with "grown up" PC's like desktops I have never changes a CMOS batery on a laptop. My friend has filled me full of scare stories like " If you take the CMOS battery out you kill the BIOS and you neeed passwords to recover it" amongst others ! Is it true? If it is how do I do it without doing what he said? Must be a way Any info gratefully accepted. Thanks in advance. Brian