2 SMTP domains in one exchange server

Hi,
Hi?i would like to have some ideas regarding adding another SMTP domain. I have read the
KB ? 289833. But I?m not sure that this is what I want ?..
Here is the situation
I already have the AD configured with one exchange server 2000? the domain is xxx.com.my .However the management set up another company and they wanted to have another smtp setup with yyy.com.my ? sharing with the existing hardware/software. How difficult or easy to done this ?.if the KB ? 289833 is what I need to do.What is the advantage of doing this ?is there any issue later or? is this advisable?.. What are other ways of doing it ?is there any??.please throw some ideas?.. Thanks