I used MultiMC to install forge and it crashed as soon as i ran the instance:
------------- MultiMC Crash Report -------------
Information:
Date: 11-04-2012 19:54:05
Operating System: Windows 7 (build 7601, Service Pack 1)
MultiMC Version: 4.2.0 jenkins-MultiMC4Windows-32
Minecraft Version: 1.4.2
------------------ Mod Lists -------------------
Jar Mods:
minecraftforge-universal-6.2.1.357.zip
Version:
Filename: minecraftforge-universal-6.2.1.357.zip
----------------- Console Log ------------------
Instance started with command: "C:\Program Files\Java\jre6\bin\java.exe" -Xms512m -Xmx1024m -jar MultiMCLauncher.jar "<username>" "<session ID>" "MultiMC: here we go again 2" "854x480"
Instance exited with code 1.
Minecraft has crashed!