Hi all,
I´ve just installed Windows Vista on my PC (p4 3.0, 1gb ram) and I had some problems with the installation.
I had this error message while starting to install: "IRQL_NOT_LESS_OR_EQUAL" in blue screen.
Now you may asking yourself "how did he installed Windows Vista anyway?"... I just got tired of trying installing and I put Windows XP to install. When it stopped copying all the setup files to hd it rebooted my pc and after that Windows Vista Setup started without any problem.
Could anyone explain how this is possible since I have XP and Vista on different partitions?
If anyone could also explain why I get this error "IRQL_NOT_LESS_OR_EQUAL"...
Thank you in advance.

In every single instance I've ever seen that particular error in a blue screen, it's been because of a device driver. Whether the driver was coded sloppy or there was just some sort of conflict between multiple drivers, I'm not sure. But usually an updated driver or a swap of hardware has always fixed it for me.