THere is almost never a problem reactivating on a reinstall to same hardware.

Only when you change hardware does it sometimes require a robocall to deactivate the old install and activate the new one.

Good advice from theog on your partitioning and backing up.

Boot from DVD, keep ethernet plugged and "connect to internet during install" to get latest drivers/updates into installer, use Custom installer>Drive Options to delete all partitions, create new ones, format all, then make sure first partition is highlighted when you click Install.

Afterwards, you wil have newer drivers in Windows Update. Any missing in Device Manager can be found quickly by backing up your windows/system32/drivers folder in advance, checking the Support Downloads page for your make and model computer, any drivers/apps CD, or Googling exact device name.