then installed the latest RTM and then Install what you need later..
Nah... better go with MS DOS, or maybe windows 98.
On a serious note, if you think 90% of the OS is useless, take the official SP1 iso, strip it down yourself and install it.
As I implied earlier, you have a wrong understanding of how an OS like windows works and how it utilizes resources. A single core Pentium 4 clocked at 3.3GHz with 2GB of ram and the onboard GMA 950 boots an updated 7 Pro SP1 x64 in about 20 seconds and has around 1.3-1.4GB of ram available at idle.
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So no, there's no point in screwing with windows if you're looking for performance. And if it's not already obvious, i'll just say it: I'm against using overly modified OSes, believing they bring more performance to the table. They don't. There's already a thread where I uploaded a clean build of 7 Pro SP1 x64 updated to september.
If you still want to play around with windows, use google to learn how and do it yourself.