You can do a simple test by pinging some device that allows ICMP traffic. If you ping your router's gateway which should be something like 192.168.1.1 or whatever, you should get a response back with the amount of time it is taking for the return reply. So just issue a command like ping 192.168.1.1 from a command window. You can then ping some public server like
www.yahoo.com and see if you get return replies. Window's default is to send 4 ICMP packets out. If you are not getting any replies back, you will get a message "Not responding." If you are losing packets, you'll get a reply back with the time it took and then withing the 4 packets sent out one or more will come back as "Not responding." If you get response to some ping requests but not all, that is known as having packets being dropped.
Hope it's not too complex the way I explained it.
Problems? See this thread at archive.org.