Windows 7 64 bit

Hi,

I have downloaded one windows 7 64 bit a long ago in torrent with activator.
I am told that some torrent might insert virus on windows itself.

I don't know whether i have downloaded a clean one or not.

This is what i have.

en_windows7_ultimate_x64_dvd_x15-65922.iso
The size is : 3149108 KB

One of my friend told that windows 7 64 bit size is : 3243070KB

So, I don't know what kind of version i have downloaded.
Where can i download good version of windows any version?

Thanks

 

I just checked and it has the right sha1
Microsoft has uppercase and when i checked i got them all in lower case. I don't think it will be an issue.

Anyway, The windows 7 came along with an activator.
I have recently downloaded MTKV249 from here. Can i use MTKV249 to activate windows 7?

Additional Question :
I want to use windows 8.1
Where to subscribe to get mail when the an activator is ready?

 

I don't have activator in my windows 7 torrent.
If, I can't use MTK, then which is the best one?

Is windows 8 taking more power than windows 7 in laptops?
I feel so. That is why i am looking for W7.

 

en_windows_7_ultimate_x64_dvd_x15-65922

This is my version. What is enterprise?
I know Windows 7 Ultimate | Pro | Home premium ..
But what is Enterprise?

For Daz (kickass.to/windows-7-loader-activator-v2-0-6-reloaded-daz-team-rjaa-t5939225.html)
Is it a good torrent?
Who is maintaining it?

 

After reading about windows version, I don't know why am i using ultimate. Because Home Premium is good enough for me. I am not using all the features of ultimate.

Will there be any performance difference between ultimate and home premium or pro?
Will home premium or pro load faster than ultimate?

And MKT supports windows 7 home premium?