I tried to install the JDK 7u4 b13 on Windows XP Pro test system with 480 Mb of RAM. Nothing happened when I run jdk-7u4-ea-windows-i586.exe.

I tried to find the any Errors in install log. Nothing for 7u2.
The "C:\Documents and Settings\root\Local Settings\Temp\jdk_inst.log" is available for JDK 7 u4:

"
Sun Mar 11 21:22:00 2012
:: Jdk installation failed. Return Code: 1, ErrorCode: 5
"

I don't know exact reason, but it seem the behavior is a regression because JDK installation is ok with JDK 7 fcs.
I assume it could be caused by Java FX integration because this is regression in JDK 7 u2.