1- Remove unnecessary start ups :
All you have to do is to type: "msconfig" in Start>Run and from the startup tab uncheck all those extra items that you don't consider as necessary. Among them you'd better avoid unchecking the items you see in this picture including your 3rd party anti virus .
2- Turn some visuals off:
Be true to your self, Do you like an animated slow environment with bells and whistels that swing around your head all the time or you prefer a fast simple operating Windows environment? If you want both, you better turn "Animate windows when minimizing and maximizing" and "fade or slide..." items off. They do nothing other than making your interaction with your system slower than ever and reduce your productivity.
3- Do a post-installation Defrag with PerfectDisk:
I bet you know how fast hard disk are today. However, even the fastest hard disk comes to a crash when it has to deal with millions of files hundreds of times a day. And the fragmentation here is the evil that can reduce you hard disk's performance and life time to a half. If you want a fast and really effective defragmentation, then you have to use PerfectDisk. Nothing beats this smart software in the way it does its job. You have to also do a boot time defragmentation to see your system performance increased.
4- Clean Temporary files and System Restores:
Removing temporary files will avoid systems errors when you install new programs. It also frees some disk space which actually makes your system defragmented much faster than before.
5- Disable indexing:
If you don't search for your lost documents frequently and have your files mostly spreaded on remote machines, or have the patience to wait a minute to find your lost documents, you can easily turn the Indexing Service off. This will be a great resource saver when you need to run heavy programs and games on Windows Vista.
6-Use NOD32 instead of Windows Defender:
Not only NOD32 performs better than Windows Defender, it also is the most successful antivirus in the world when it comes to finding zero day threaths. You can turn Windows Defender off by goining to: Start>Control Panel>Windows Defender>Options, and Turn all Windows defender options off.
7- Disable User Account Control:
I know you hate the infamous pop-up window that asks you if you really want to do something... and who doesn't! Not only it is a boring repeated procedure, but it also makes you think your system is very follish in determining who is behind a certain action. To get rid of it, Simply go to: StartUp>Control Panel> User Accounts Control>Turn UAC off /on Remember than you have to reboot your system for this procedure.
These 7 tips are what I perform after each Windows Vista installation, because I know that without them those tweaks my clients will-in less than one day or so-ask me for a clean re-install of Windows XP !