1. I am using red hat linux distribution. May i know except fedora linux, CentOs linux, still have any distribution similar red hat distribution.

2. I have 2Pcs system, 1 is latest modern hardware system, this system i can just install the latest redhat distribution, except fedora linux and CentOs linux still have any famous powerfull latest Free distribution to use? please recomment me.

3. The other second old hardware system, this system cannot install latest redhat distribution, so please just recomment me which not free like redhat distribution and Free like redhat distribution linux to use on this old hardware system pentium 3 500Ghz,128mb ram, 10gb hdd.

Thank you.

Ad 1:
http://en.wikipedia.org/wiki/Red_Hat...e_Linux_clones

Ad 2:
This question has been asked a million times. In my opinion it highly depends on what you want to do with it. Look at http://distrowatch.com/ for the more popular ones.

Ad 3:
With the risk of forgetting a number of distros: Xubuntu, DSL, LFS, Slackware

On the PIII the shortage of memory is what is going to be more of a problem than the cpu. I have a PIII 1ghz with 512mb that I use as a media server. It run Centos5 without issue. At the price of memory now I would think it would be better to keep both machines on the same "blood line", ie I run Centos5 on my servers and F7 on my desktop.