NIS 2009 on network with McAfee

I have been a McAfee user for several years and have just purchased NIS2009 because of the excellent reviews in the trade rags.  My question . . .  I currently have 3 pcs in my home network that have McAfee licenses good thru 7/2009.  I am adding a new pc with no security software & want to know if there are any concerns with adding it to the network & installing NIS 2009 with other systems running McAfee.  Plan is to eventually replace McAfee with installs of NIS 2009 on all if I like.  Also, any issues with installing NIS 2009 after removing McAffe?