Background bandwidth usage

[#1]

View My Usage is showing background traffic at twice the normal levels I'm used to seeing. Previously it was around 40-50kB every hour, now its around 100kB. I realise that this is small beer in comparison to monthly allowances, but what could have caused the increase? Is this something I should be concerned about? What is considered 'normal' levels?
In case it is of any significance, my router was powered down for 7 days and the increase is only since it was powered up again.

[#2]

Morning Maranello.
From what I can tell, you use a Dynaic IP Address.  It's possible that the increase in traffic (albeit small as you point out) is related to the change in IP.  If you reboot again, you should be assigned a different address, which I suspect may result in a different level of traffic.

[#3]

Hi Jameseh
Thanks for your prompt reply. You correctly deduced that I do not have a static IP addess, and I'm guessing that the one now assigned could be seeing an increase due to some malicious attempt to hack in to my PC. Would this be stopped by the hardware firewall? Could this also be responsible for difficulties I had yesterday in updating my AVG virus database version?
I'll try a reboot tonight to see if it makes a difference. What are the chances of getting the same IP address on reboot? I'm using a D-Link 2640B, any idea how  I find out the IP address assigned?

[#4]

Hiya,
You can find out your IP address by going to http://www.whatismyip.com
I wouldn't necessarily be worried about the increase in background traffic and I don't think it's necessarily malicious.  Also your router firewall will be acting accordingly otherwise your usage will have been a LOT higher!
Don't worry about it too much

[#5]

could of bein that the previous user of that ip was running a p2p client. the trackers of torrents can and do some times still tell other users the ip address is still runing the client for some time after and the increase in bandwidth is other users p2p clients trying to connect but as soon as it gets to your router there told to buzz of because the port is not open.
if it was some one trying to hack and had bein sucesfull the amount of bandwidth would of bein alot higher.
nothing to worry about. as jameseh says new ip and the traffic should go back to normal