I just purchased a nice big external hard drive to plug into my Airport Extreme base station to function as a network drive and central backup spot. While I have yet to upgrade to Leopard, it is likely that will happen in the near future so the following tips and tricks on backing up with Time Machine are ones that anyone in my position would find useful.
Arstechnica has put together a nice simple primer for someone stepping into network storage and backups for the first time. The main issue with time Machine is that it backs up every hour, there is no setting to do otherwise. While this would work just fine for some, If you think that this will slow your machine down too much and too often you will have to resort to a separate utility to get around that or wait until Apple issues an update to include that setting.
Read more of the tips and tricks here