pinging your pc from your PC won't tell you much mate, what about pinging another computer on the lan or net ?
On XP ; Start, Run, type 'cmd' without the quote's and then type 'ping apple.com ' and hit return. if you want to ping another IP instead of a domain type 'ping 17.254.3.183' or whatever IP you want that one is apple.com.
If you are getting poor pings or time out's try 'tracert apple.com' and this will show you the hop's your ping packet takes to reach the destination host allowing you to work out if the problem is in your LAN, your ISP's side of things or beyond.