A DSL connection uses dedicated bandwidths for upload and download (you should know that: that's the reason why you have 6Mdown /512Kup).
I would nonetheless try some of these out. Also, it could be that you aren't connected to all 8 hosts yet. Give it time to connect to all of them.
Also, a T3 host has waaaaay more upload bandwidth that a Cable/ADSL user, so dlding from T# connections should help increase dld speeds (you should be careful of some T3 users though: some serve fake files)

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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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