Formatting + re-installation only OS partition without "System reserve" MBR partition possible?

On my hard disc there are (among others) two primary partitions:
.....
2. primary partition "System Reserve" Active=yes NTFS 100MB
3. primary partition "winos" active=no 30 NTFS GB
...

As far as I understand partition no 2 contains the MBR and a link to partition no 3
So at bootup at first partition no 2 is called which in turn starts the OS on partition no 3.

If I format now partition no 3 and re-install win7os on partition no3: does that work? In other words: do I have in addition to re-write or adjust somehow partition no 2?

Or can I simply replace the stuff on partition no 3 and everything works fine?

Peter