Hi
you can add 2.6.20 kernel to the existing one. download the required kernel (2.6.20) and use in your machine.
search for
linux-2.6.20.1.tar.gz in
Index of /pub/linux/kernel/v2.6 and download .
how to compile and install
#tar -zxvf linux-2.6.20.1.tar.gz
#cd linux-<version>
#make menuconfig ( for customizing )
#make
#make modules_install
this may take around 2 hours.