Windows XP support officialy ends today.

[Squall]

I like XP, it is the best Windows version ever.
The reason to use Windows 7 is the hardware support, which includes drivers and Directx 11.
Directx 11 is not important for me, because the system requirements of games that use it are way high.
I do not know Windows 8, but it seems it is as terrible as Vista.

Everything that comes with Windows is pretty useless (Internet Explorer and other things that I have never executed). Everything that I execute is things that I had to install.

Any Windows is not secure, no matter if it is new or old. Anti-virus are not perfect and may fail.
If the number of users of a system decreases, the number of viruses will also decrease.
If you want a secure system, use Linux. Lubuntu 14 LTS will be released this month.