Which partitions should I delete before doing a clean install?

[Incredibruin]

Here is the list order in Windows 8.1.

Name: Drive 0 Partition 1: SYSTEM, Total size: 100MB, Free space: 70B, Type: System
Name: Drive 0 Unallocated Space, Total size: 900MB, Free Space: 900MB
Name: Drive 0 Partition 2, Total size: 128MB, Free Space: 128MB, Type: MSR (Reserved)
Name: Drive 0 Partition 3: OS, Total size: 930.4GB, Free Space: 908.9GB, Type: Primary

I believe Partition 1 was the Healthy EFI System, but I am in need of some advice.

UPDATE: Also, this is my first time installing an OS, so I am I supposed to delete and make a partition on 3 again or do I install it on unallocated space?

 

[drykill]

(Name: Drive 0 Partition 3: OS, Total size: 930.4GB, Free Space: 908.9GB, Type: Primary)

delete this one.. ^_^

 

[Incredibruin]

(Name: Drive 0 Partition 3: OS, Total size: 930.4GB, Free Space: 908.9GB, Type: Primary)

delete this one.. ^_^

That 900MB unallocated space is bothering me even though it is a meager 900MB, do I make a partition on that and extend it to the OS or just leave as is? (I am not sure if the MSR appears in Disk Management, so I would like some reassurance that the unallocated space and Partition 3 will be adjacent)

 

[HEXiT]

if you have a disk to install from delete them all. and create 2 new partitions. 1 250gig for the o.s and the 2nd for storage using up the rest.
if your version of windows use crypt locker it will create a 3rd of 100mb(win7) or a little larger if you use win 8/8.1 called reserved.
1s done you can install windows on the first partition which will be on the outside of the disk. so will give the fastest access, just as it should be.