About a decade ago, a friend introduced me to Linux and installed YellowDog Linux 2.1 on my then-aging PowerMac 6500/300.
The X-windows system ran frustratingly slowly in both KDE and GNOME, but especially KDE. It ran marginally faster in something he added called Windowmaker.

I wrote it off as the machine being too slow. However, recently I saw somebody running either Red Hat or Fendora on a 250mhz pentium II machine. I was able to run Firefox at a reasonable speed for the machine.Given that that former "wintel" machine had a 32-bit processor and the PPC 603ev is a 64-bit processor and is 50mhz faster, I'd assume I should have been getting comperable performance, but I don't. I'd like suggestions on what distributions I can use today besides Yellow Dog.



Back when YDL 2.3 and 3.0 came out, I had difficulty upgrading. mostly with the video not working right.
I realize that the old 6500/300 is hopelessly obsolete, and the only reason I keep it around is to use as a TV set and occasionally display text files downloaded from Gamefaqs.com.
I'd like to be able to use Linux to breathe new life into the machine and make it once again useful for basic web browsing as well like it was 5 years ago.

I may be asking a lot of the old machine by trying to use it for browsing the web today like I used to in the past, but if I'm going to keep it around, I'd like it to be as useful as possible.

So, what distributions will work on the old PowerMac 6500/300 with 128mb of RAM and a 20gb (ext2 partition, the rest are hfs+ partitions except for the 128mb swap) hard drive?

OldWorld Mac can use debian. You'll need to use a boot loader adapter- forgot which one- to load the system. Bootx, that's it.
You then have to find extra instructions on using this. I believe older gentoos allow such.
Here goes the catch, you then have to upgrade everything after you install. I'm not trying to discourage you, I'm letting you know there is work to be done. Be patient through this part.
There's a howto on debian forums.

I would also say use a netinst of Debian. I did it on an older G3 imac, I think a 300mhz with 128mb of ram. I used fluxbox as the window manager, ran pretty good. I still have the machine but hardly use it anymore.