I've been having probs with my internet speeds for well over a month now. However, I seem to have drilled it down to not being anything to do with my ISP or telephone line.
The basics: i'm on Virgin ADSL with a max of 2mb connection. For well over 2 years now I have had a solid 1.8 download speed (checked thanks to the speedtest at thinkbroadband.com) on their Port 8095 test. Never had any problems.
Then, whilst playing Call of Duty 4 on a German server (i'm in UK), on which I always got around a 40 - 60 ping, I started getting 150 to 250 ping. No slowdown on websites though. So ran the speedtest and now I get 0.1mb download all times day/night. But if I run with the Port 80 option ticked, then i'm back to my old speeds again.
Checked with Virgin and i'm not being speed throttled, took my PC to a friends house who has an 8mb BT Business connection via a network (so not on my USB modem), and got exactly the same results - 0.1mb download. But again on the Port 80 option, I get much faster speeds (equivalent to what my mate gets normally)
I have even reformatted and reinstalled Vista 32, ran the speedtest without my AVG firewall turned on but still to no avail!!!
I cannot think of anything I have downloaded that has made a change outside of the usual Vista updates.
Sorry for the long post, but please any ideas would be very gratefully received.