[adulau]

If you want to reuse your old PowerPC hardware, you still have the option to run a recent version of GNU/Linux. Ubuntu 10.10 (Maverick Meerkat) has a recent version (ubuntu-10.10-desktop-powerpc.iso) for PowerPC Mac.

[vetinari]

Many ppc Macs use nvidia graphics. There is no proprietary nvidia driver for powerpc.

On the other hand, 10.5 runs fine on ppc. As a poster above noted, your old OS does not magically stop working after release of new version.

[rbarooah]

Although you could just keep running leopard.