Virgin's DNS Server addresses are 220.127.116.11 and 18.104.22.168
Alternatively, you could use the OpenDNS servers whose addresses are 22.214.171.124 and 126.96.36.199
You could also use your Router's IP address as the PC's DNS Server address.
>>> when I do ipconfig/all its lists DHCP as not enabled.
That's correct. If you haven't selected the options to obtain both IP and DNS Server addresses automatically in the TCP/IP settings, DHCP is disabled.
You can have the IP address obtained automatically by DHCP and assign fixed DNS Server addresses, but not the other way round. If you allocate a fixed IP address, you must also allocate the DNS Server address(es).