Tiger updating problem... Please Help!

You could try manually installing the Intel update, for some bizarre reason your software update could be downloading the PPC update. But in any case, make sure that you run Disc Utility and repair permissions at each step (after the initial install, then after each update/restart and any other installs you do). Otherwise, you can try booting into single user and running FSCK, that usually sorts out stuff for me.

And also try being patient. The first time you reboot after installing or updating Tiger, it takes a VERY long time to boot (on my G5, the last update took about 5 minutes to load on the first restart, was fine after that). Not sure why, but I'd guess that most of the kernel file replacement (i.e., the central part of the install) is probably carried out during that first boot...

Finally you could try downloading a torrent of the current (10.4.11) Universal build of Tiger. Technically I don't think this would be illegal, since you have a license for Tiger, but I'm not 100% on that (I doubt you'd end up prosecuted for it at any rate).