what plans were you contemplating? how much money were they planning to spend? Avoid telstra like the plague
http://www.whirlpool.net.au has a good plan comparison section.
Unless they are planning to choose the really weird "starter" 200M/500M a month plans they should be OK. It is also worth looking at what games they will play and whether the ISP has their own gaming servers.
I've had a good experience with Internode as an ISP - their tech support is really good, and from memory they have a short contract period, though the only connection I can get where I live is optus cable, so DSL is a can't have.
It also might be worth looking at whether they are in an area where some of the non-Telstra ISPs are putting their own equipment, as you can get much higher speeds (up to 8Mbit).
Sorry - didn't really answer your question, but hope that is helpful
