HIYA, just signed up to these forums so i can add something to this particular discussion, i am having the same problem that the OP is having I just moved house and went from virgin cable 10meg to virgin adsl "up to" 8meg (as theres no cable round these here parts) and ever since i have not been able to get more than 62.4 kbps out of downloading games from steam. no matter what time of day no matter what game (borderlands update, tf2 update, stalker CoP) no matter how many times i switch dl region no matter how many times i delete clientregistry.blob a steady 60 kbps. picture proof of what i'm talking about: http://www.ukmandown.co.uk/files/public/1267263328_351_FT0_speedtestnewhouse.png even though i can download video mp4 files from youtube at 500 kbps and also downloaded acrobat reader at 600 kbps, i still only get 60 kbps from steam. Virgin have been useless on the phone and have got me doing a second lot of tests from http://speedtester.bt.com
Safari you could try and post here http://community.virginmedia.com/t5/Broadband-down-your-phone-line/Poor-speeds-on-Virgin-National-service/td-p/27792/page/16 good luck with that though as VM support is a joke!
