You would need a SATA to IDE interface converter but I doubt you could get it to fit without some modification and they can also cause data corruption.
Your best bet is to sell the SATA drive and use the money to put toward a new 2.5" IDE.
i used to have a ppc mini....i ran leopard after upgrades
besides upgrading the mem to 1 gig...i found upgrading the internal harddrive to a more modern (as modern as ide is these days) made a hugh difference...i fact it made a way bigger diff then even the mem upgrade ...as far as speed went...
ps: use a medal putty knife to open case...slide in sides and then pull outward...both mem and hd upgrades nice and easy on a ppc mini