To Prevent SMS 2.0 from discovering and installing SMS 2.0 client software on specific computers, use Regedt32 (on the SMS computer) to navigate to:
On the Edit menu, Add Key name SMS_DISCOVERY_DATA_MANAGER. Select the SMS_DISCOVERY_DATA_MANAGER key and Add Value name ExcludeServers, as a type REG_MULTI_SZ. Enter the Windows NT Computer Name(s) you wish to exclude, one per line. Click OK when you are finished and Exit Regedt32.