Salut!

Well, Wanadoo doesn't have anything indeed that chokes P2P. The only thing they do is that they automatically cut your connection after 24h of use to change your IP (it's all about that dynamic IP thingy). I've also got Wanadoo and I can tell you that their service is indeed OK.
Anyway, try disabling the firewall altogether. Might work.

btw, how come you aren't using an Ethernet modem? Just go ask for one (normally, it should be given for 1€ when you got your connection). I read that USB ones can be a pain.

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iMac G4 OSX 10.3.9
RAM 256MB
LW 4.10.5 Basic
ADSL anything from 3 to 8Mbps/around 1024kbps

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