Things I do first before/after installing a Windows OS:
Partition the HDD so that ONLY the actual OS resides in the first one, all other software is installed in a separate partition, which makes defragmenting faster and more efficient, and uninstalling programs easier.
Move the Windows "page file", which is the equivalent of the Linux OS' "swap file" into its very own partition, preferably on another partitioned HDD and in the first partition for faster access. The page file being created with same max/min size of twice the size of the PC or laptops' physical RAM memory.
Download and install CCleaner in order to wipe and delete leftover temp files from installs/uninstalls, cookies, history and Flash LSOs, after browsing the internet with my browsers of choice.
Download and install Clam AV, which is a free "cloud based" antivirus software program that can be run alongside another installed AV software like Avira, Avast, ect...making it so there are more options to stop viruses, trojans, worms, and the like. Also connect to the internet with a router for a hardware firewall protection, and download and install a free software firewall, such as Comodo or Zone Alarm.
Download and install ZSoft Uninstaller, which is the BEST freeware program that I have found, that not only uninstalls software programs, but ALSO will delete ALL of the Windows registry entries that the default Windows uninstaller or other software programs will often leave behind. It can be installed into a Windows HDD partition, OR optionally into a thumbdrive for portability as well.
Backup the Windows Registry AND backup the Windows OS with a dedicated EXTERNAL HDD.
http://www.zsoft.dk/index/software_details/4
I could write a booklike blog here detailing all of the stuff that I do with Windows to tweak , hack and improve it, but IMO, everyone who is less than a tech geek, who uses such a juicy target OS for attacks by hackers, trojans, worms, and viruses, that is and uses a very vulnerable flavor/version of a Windows OS on the internet SHOULD buy a used Windows-based instruction-guide book from Amazon or eBay or a bookstore or library to LEARN about how to use it PROPERLY to stay safe and secure. There are also many websites online that also have help guides, of course.