Does sin befall me for repairing and maintaining computers that use pirated software, specifically installing pirated Windows, knowing that I refrain from installing the rest of the pirated software requested by the customer?

You are not permitted to install the aforementioned program or any other pirated software without the permission of its owners, even during maintenance and reinstallation. You should make this clear to your customers, for the Prophet, peace and blessings be upon him, said: "Religion is advice."