HELP!! I have a Dell Inspiron 531 with a Trojan. Its changed the size of my C and D partitions, and now I cant download any

[The Boles Family]

I have a Trojan that resized my C and D partitions to the point that my PC is unusable. When I try reloading my OS, it creates a file "Windows old", which is where the Trojan is. It then reinfects my new download. I cannot delete the files manually either, its telling me I dont have permissions. WHAT CAN I DO?????

 

[Someone Somewhere]

When you reload the OS, you need to hit the Advanced button, then format the partition before you install.