I use window xp version on my desk top computer. I am not able to connect to the internet I push connect and it makes the dialing noise but doesn't connect. It gives me an error message 678 that a connection can not be found. Please help

That's a catchall error to some extent and can also be caused by damaged networking components. Confirm the phone number being dialed and see Microsoft Article on Error 678 after installing Windows XP Service Pack 2 (http://support.microsoft.com/kb/892889) if it applies. Enabling and viewing modem log (http://www.modemsite.com/56K/modemlog2k.asp) and ppp log (http://www.modemsite.com/56K/ppp.asp) can help determine where the connection attempt is failing. Issuing "netsh interface ip reset log.txt" at a command prompt will reset TCP/IP. (Note you will need to reenter any static addressing on your network adapters after issuing the command.)

Here is a link with some troubleshooting, don't worry if you do not have netzero, issue is the same
NetZero Support - Error 678: Remote modem not responding- Free Dial Up Internet Service - High Speed ISP - Net Zero Internet Provider - Netzero.com (http://www.netzero.net/support/errors/error678.html)

Here is another link to check out if above does not help
You may receive Error 678 or Error 769 when you try to connect to the Internet or when you try to browse the Internet after you install Windows XP Service Pack 2 (http://support.microsoft.com/kb/892889)