effect of traditional ajax calls for my website

[Morpheus]

I am building website its homepage has two grids that I want to update say 1 minutes or above.. I have used the traditional ajax calls to update the grid after one minute.. Now I have become aware of long polling and websockets.. the question is that should I leave the old way or change it to push technology?? Will the growth of users effect the system if yes then what is expected frequency after which the system will respond in unbehaved way? any suggestions will be greatly appreciated.. Thanks