How can I wipe clear all data on pre-owned/used PC?

Did the seller, sell you a PC & Windows 7 COA?

Well initially he told me vista, but he's not very computer avvy, as it came from a small office he ran. He specified, NO windows disk. So its all fair. Just want to keep the windows 7 now, as it is a joy to use, but want a wipe, just to be on the safeside

So he sold you a PC with no OS.
You need to buy a COA.

How much is that? And where can I purchase one? Can't I just get an iso of the dis, and use my product key?

The COA is the product key.

Well I have one of those on the version that is installed. The 25 digit key. And it all tested as genuine through Microsoft's verification

What is the wording?

As previously mentioned, I have no sticker, but when I get the info, up on the system, it clearly states, windows 7 ultimate edition 32-bit

theog said:

Did the seller, sell you a PC & Windows 7 COA?

Yes or NO

Huwey said:

Well initially he told me vista, but he's not very computer avvy, as it came from a small office he ran. He specified, NO windows disk. So its all fair. Just want to keep the windows 7 now, as it is a joy to use, but want a wipe, just to be on the safeside

theog said:

So he sold you a PC with no OS.
You need to buy a COA.

He sold me a pc, with windows 7 ultimate preinstalled, by him. If by COA you mean sticker, no, there was none, as he put it on there himself