This is all you have to type:
ping www.altavista.com
If the output is something like this, then you have DNS issues. Just contact your ISP and tell them your problem.
C:\Documents and Settings\cgkanchi> ping www.altavista.com
Ping request could not find host www.altavista.com. Please check the name and try again.
Otherwise, if it's something like this, you have other issues.
C:\Documents and Settings\cgkanchi>ping altavista.com

Pinging altavista.com [66.218.71.198] with 32 bytes of data:

Reply from 66.218.71.198: bytes=32 time=317ms TTL=240
Reply from 66.218.71.198: bytes=32 time=317ms TTL=240
Reply from 66.218.71.198: bytes=32 time=316ms TTL=240
Reply from 66.218.71.198: bytes=32 time=315ms TTL=239

Ping statistics for 66.218.71.198:
Packets: Sent = 4, Received = 3, Lost = 1 (25% loss),
Approximate round trip times in milli-seconds:
Minimum = 315ms, Maximum = 317ms, Average = 316ms
Also, could you just post the contents of your C:\Windows\System32\drivers\etc\hosts file (just open it in notepad and copy/paste it here), that's one possibility that hasn't been checked.
Cheers,
cgkanchi