Experts, I am planning to create a test environment for SCCM 2007 R2 and servers are SCCMCENSRV, SCCMPRISRV, SCCMSECSRV and Client System SCCMCIENT1. Planning to test the Software DP, SCCM Client installation and WSUS Sync. Question is can we setup the SCCM 2007 R2 without extend the Schema? what is the impact? Can we use the WINS?

It can be done, but life is easier if you extend the schema. See http://technet.microsoft.com/en-us/library/bb694066.aspx ("Decide If You Should Extend the Active Directory Schema")