I read the Sticky post and included all the requested information.
I started with a clean install(no old copies MC installed) of minecraft 1.2.5 with the intent to run RedPower2.( have tried more then once to install from fresh, same results) I first installed Risugami's Modloader for 1.2.5 by opening the minecraft.jar with Archive(linux) as I have for other mods in the past and copied over the files from Modloader zip and Delete META-INF, then I closed every thing and ran Minecraft from the terminal with "java -Dsun.java3d.opengl=true -Xmx1024M -Xms512M -cp minecraft.jar net.minecraft.LauncherFrame" and checked that minecraft works, every thing is fine at this point. Then I try to install Forge with the same installation method(Forge Wiki install instructions) of copying ALL the contents of the zip to minecraft.jar in /.minecraft/bin/ and when I try to run MC it just gives the above posted output from the terminal and a blank screen. As far as I can tell I'm not doing any thing wrong with the installation as per Wiki and I have used MC mods in the past (BuildCraft) so installation is not new to me, just hope there is some way to fix this or get it going.