Custom install Windows 7 but have double OS files due to OEM partition

Hey all!
I have a Acer Aspire 5735Z with a 160GB hard drive which is split into 3 partitions (C: , D: & OEM Reserved Manufacturer) running Windows 7 Ultimate x64. The original OS was Windows Vista Home x32. I did a custom install of Win7, leaving all partitions as they were (besides overriding the C: one) and everything went smoothly. Now a month later i realize that i have all the old Windows Vista files along with the new Windows 7 ones. It does not create any problems as it runs exept when updating were the system goes off and then everything is peachy again. It does take up a lot of disk space. So I want to do a clean re-install of Windows 7 Ultimate x64 to "fix" it and while i'm at it get rid of the multiple partitions. I know how to do a custom install and how to make these 2 partitions go away obviously, but i have no idea what "role" the 3rd partition plays in the mix. I get that it is something system related. I was thinking that this "OEM" partition might have something to do with the double OS files? So Is it safe to delete it? Or do i leave it, delete the other two partitions and do the install again? Maybe i messed up somehow..

The OEM reserved manufacturer partition either has some special OEM supplied tools on it or is to be used to restore the machine to factory specifications as of the day it was manufactured.

Regardless, you don't need it if you are going to do a clean install and have no intention of ever going back to factory specs--which would mean Vista.

There's a pretty good chance that reserved manufacturer partition is useless anyway because you've already installed Win 7 over Vista.

I'd back up my personal data, boot from the install disc, delete all 3 partitions when you get to the "where do you want to install Windows" screen and install to that unallocated space.

You should end up with a system reserved partition and C. Nothing else.

After you finish the install, you can then shrink C and make a new D if you want to use a D partition for data. Or you could make a C of a particular size during the install immediately after deleting all partitions, rather than just installing Windows to the entire unallocated space. And then make a D of the remaining space after you get Windows installed.

I did it. Erased it cause it was useless since i won't ever go back to Vista and made all partitions into unallocated space and installed there. Everything went smoothly!
Thanks for the help!

If you ever do it again you might want to follow these steps for Clean Reinstall Windows 7 which have helped over a million users get and keep a perfect install. Everything that works best is included based on tens of thousands of installs we've directly helped with here since beta.