It is likely that upgrading to SLES 10 SP2 and then installing the bigsmp kernel will be the safest way.

The only thing my goal is that want to let the kernel addressable above 4GB memory with the help of bigsmp and use it accordingly . So would the bigsmp kernel do install in the place of smp kernel automatically and yast can addressable its 8GB memory if i go through the current SLES 10 sp1 to SLES 10 sp2 up gradation or later one?

The client requirement is very simple ,would like to let know the 8GB memory to OS and utilize it.never concerned about the latest patch features and stability.