Windows registry cleanup and disabling autorun

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Some malicious softwares can use Autorun to infect your Windows PC.
You can disable this feature using TweakUI on WindowsXp.
If you are not using XP, search www.microsoft.com or google to find out
how to disable it.
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Today I uninstalled a lot of programs on my XP machine, since I thought
a large registry may result in slower performance. After that I was about
to run a registry cleanup tool when I read this :

"
There are a number of problems with the concept of a registry cleaner. Most notably, there is no reliable way for a program to know whether any particular key is 'junk' or not. Windows is closed source, so registry cleaner designers can not know for sure whether any particular key is still being used by Windows or what detrimental effects removing it may have; leading to examples of registry cleaners causing loss of functionality and crashes.

With regards to performance, whilst on Windows 9x computers, it is possible that a very large registry could slow down the computer's startup time; the on-disc structure of the registry is entirely different on the NT line of Operating Systems (including Windows XP and Vista). Slowdown due to registry bloat is thus far less of an issue in modern versions of Windows. More importantly, however, the difference in speed due to the use of a registry cleaner is negligible: rarely do they remove more than a few kilobytes from the total size of the registry. In fact, technology journalist Ed Bott has claimed that no-one has ever succesfully managed to measure any significant performance increase from the use of a a registry cleaner. Any potential user of a registry cleaner must thus balance a probably negligible perfomance increase against a non-zero possibility of system instability.
"
Source : http://en.wikipedia.org/wiki/Registry_cleaner

So, I dropped the idea of using a registry cleaner.