Hello,
My connection to the internet is just about constantly active, I have antivirus installed and it hasn't picked anything up in a scan, a basic 20 minute browse doing nothing special can easily be 300~400mb every time

Any ideas?

Cheers
David

if its a wireless connection I'd say one of your neighbours is enjoying free internet

Is it wifi

It's not wireless I'm connected by good old fashioned wire

Cheers
David

but is it a wifi router ?

Good old windows auto update downloading xp sp3 continually!!! Adobe updater service is also a sod for using all available bandwidth, you using a torrent/peer 2 peer network that people could be connecting to you and uploading?? Just a couple of ideas.

Cheers

Rich

Try zonealarm, its a freebee firewall that allows you to control which programs access the net.

netstat -a is useful, but you can use tcpview: -

http://technet.microsoft.com/en-us/sysinternals/bb897437.aspx

Shows current network connections in realtime. Boot your PC and make sure you're not running anything else, launch tcpview and see what's connecting to where.

Sounds like your PC that has been turned into a spam bot.