I'm wondering about how packets are sent to game servers. I have noticed I get 'very high' pings on the WA GameArena servers (120-130 average) which seems odd, and better ping to Adelaide servers (75-80). On Internode servers I generally get pings of about 80. The best ping I will get on any server is about 70.
The average for most servers I am on is about 40 (Internode / GA BF2 servers); I am generally the highest ping on any Australian server I am on.

Are there any diagnostics i can run locally to see what is going on?
If this is the case, would I be likely to see a vast increase if I changed to an ADSL2 plan?
Obviously these pings aren't ideal, and i'd like to diagnose the cause and find a solution; far more preferrable to me than churning to a local ISP like iiNet - or would this be the only realistic alternative?
Thanks for all help/advice offered.