The DNS Client service is not necessary and can cause huge system slowdowns if you use a HOSTS file from hpHosts or MVPS.
Disabling the Windows "DNS Client" service:
http://www.simpledns.com/kb.aspx?kbid=1089
I recommend OpenDNS:
https://www.opendns.com/homenetwork/start/computer
Install a HOSTS file to prevent known malware sites from accessing your system.
HOSTS files I use:
http://www.mvps.org/winhelp2002/hosts.htm <== includes good guide
http://hosts-file.net/?s=Download
Managed with HostsMan and I use its HostsServer proxy to speed up browsing:
http://www.abelhadigital.com