Clients on the single server?

Hi,
I am wondering about how many clients to put on one server to get it working stable and face minimum problems if something bad...

Source: http://www.webhostingtalk.com/showthread.php?t=1077690&goto=newpost

http://www.basishost.com http://www.basishost.com/domain/ http://www.basishost.com/hosting/ http://www.basishost.com/vps/