Virus hit my laptop..weeks ago..T.T

Yup..my laptop have being hit by severe trojan virus which is unstop able at my laptop after i try to download some files from the internet..it directly uploading the files from my laptop to the internet continuously...after the connection were establish..not just that...The virus also help to slow down the router as well as my friends using the same connection unable to surfing website after my laptop is connect to the router..
But after i disconnect from the router...my friends internet connection goes as fast as the speed given..i got another way to solve this problem but i wanted to reformat my laptop so badly because i already use my laptop without reformat for almost a year...what Operating system i used??Its a crack version window 7 Ultimate x86...taken from my friends...lol









Whatever i'm a newbie in laptop..so not that good in computing knowledge..But this is the problem i faces and the way i solve my problem..then all the previous data is gone case...sad><