Can we Install Operating System on client Machine directly from Network without using CD,or Images ?

Yes you can install by using OS deployment tools, Following freeware softwares are good

1. FOG

2. Microsoft deployment tool (MDT) using Windows Deployment Service (WDS)

above softwares support both Windows XP and Windows7 installation

For Operating System Deployment you can use:

System Center Configuration Manager (SCCM).

Windows Deployment Service (WDS).

Yes if it is available on the server.

Yes through server...

Yes we can if there is a WDS available in your network.

YEs through WDS server and you also install windows through usb

Yes.

Yes we can. We need to have WDS and PXE enabled in ethernet card.

YES ! WDS, OR Acronis Snap Deploy.

yes by Using "WDS"

Windows deployment Service

Check this Link:

http://technet.microsoft.com/en-us/library/cc771670%28v=ws.10%29.aspx

Yes we can install operating system with out cd or images using window's deployment service and u can even install softwares to systems using software deployment service.