Un-explained Download Usage

Possible reason for unexplained usage: Please bear in mind it only calculates http traffic and is not a true indication of usage
Even though your computer is turned off, your modem still maintains a connection to the Internet because your modem holds your user name and password to connect on to the Internet. This explains the 24 hour connectivity, as your modem is still turned on.
Also, you might be asking then how is the connection possibly downloading if the computer is turned off? This is due to "Internet noise" which is created by 'port scans' and 'ping requests'. These are usually performed by hackers, but this is not always the case. It can also be computers unknowingly infected with viruses trying to send data to your connection to determine if your computer is vulnerable or not. Since your modem has an inbuilt firewall, these requests are received (downloaded) but not passed through to your computer because the firewall blocks it. If these "attacks/attackers" are harsh enough, download usage can easily surpass the 200 megabyte mark.

What is a DDos attack? Please read http://en.wikipedia.org/wiki/Ddos

What are Ping Requests?
Ping requests are sent out over the Internet to see if you are connected or not. If you are connected, the device receiving (downloading) the request will reply with an acknowledgment. Please read http://en.wikipedia.org/wiki/Ping for more information.

What are Port Scans?
These are scans run remotely to see if your computer is vulnerable or not, in order for this to be achieved, data is sent to your modem to see if it is vulnerable or not. Please read http://en.wikipedia.org/wiki/Portscanning for more information.

Internet noise is extremely common on the Internet. As your modem has a firewall, it blocks almost every ping request and port scans. However it cannot prevent that data being downloaded to your modem. Thus, the usage recorded between 11-02-06 to 19-02-06 are legitimate downloads counted towards your download quota.

As stated by you, it is highly unlikely that someone has hacked into your wireless network or used your computer while you were away because the usage amount would be a whole lot more.

The only way to avoid this type of "unexplained" usage (and as mentioned before), is when you turn your computer off, it is recommended that you turn your modem off at the power  Possible reason for unexplained usage: Please bear in mind it only calculates http traffic and is not a true indication of usage
Even though your computer is turned off, your modem still maintains a connection to the Internet because your modem holds your user name and password to connect on to the Internet. This explains the 24 hour connectivity, as your modem is still turned on.
Also, you might be asking then how is the connection possibly downloading if the computer is turned off? This is due to "Internet noise" which is created by 'port scans' and 'ping requests'. These are usually performed by hackers, but this is not always the case. It can also be computers unknowingly infected with viruses trying to send data to your connection to determine if your computer is vulnerable or not. Since your modem has an inbuilt firewall, these requests are received (downloaded) but not passed through to your computer because the firewall blocks it. If these "attacks/attackers" are harsh enough, download usage can easily surpass the 200 megabyte mark.

What is a DDos attack? Please read http://en.wikipedia.org/wiki/Ddos

What are Ping Requests?
Ping requests are sent out over the Internet to see if you are connected or not. If you are connected, the device receiving (downloading) the request will reply with an acknowledgment. Please read http://en.wikipedia.org/wiki/Ping for more information.

What are Port Scans?
These are scans run remotely to see if your computer is vulnerable or not, in order for this to be achieved, data is sent to your modem to see if it is vulnerable or not. Please read http://en.wikipedia.org/wiki/Portscanning for more information.

Internet noise is extremely common on the Internet. As your modem has a firewall, it blocks almost every ping request and port scans. However it cannot prevent that data being downloaded to your modem. Thus, the usage recorded between 11-02-06 to 19-02-06 are legitimate downloads counted towards your download quota.

As stated by you, it is highly unlikely that someone has hacked into your wireless network or used your computer while you were away because the usage amount would be a whole lot more.

The only way to avoid this type of "unexplained" usage (and as mentioned before), is when you turn your computer off, it is recommended that you turn your modem off at the power when it is no longer neededwhen it is no longer needed