A Logical drive is only contained within an Extended partition and it is separate from the Windows 7 Primary partition and it will not be deleted by reinstalling Windows, have a look at this tutorial at the link below for more basic information on the creation and use of Extended partition / Logical drives.
Just be advised mate that we are seeing real issues created by the use of that software that are causing some people to lose data, if I were you I would copy out or make back-ups of the data and delete all that you created using that S/W and recreate what you need using Windows 7, Method One in the tutorial I listed.
Yes you're all set: Just boot the installer, make sure you select C partition, double then triple check you haven't selected the wrong partition, then Install. The installer will not touch another partition.
I use PW quite a bit
BUT I suggest you use the mini Tool (installed version) with caution. The applications has crashed on me a number of times and would never do any significant partition work with it. This experience was not work on the OS disk.
The bootable version has proven totally reliable so far.
My Computer
At a glance
Windows 7x64 Home Premium SP1Intel i7 2600kG.Skill Ripjaws (DDR3-1600) 2x4GBNvidia GeForce GTS 450; Intel HD Graphics 300...
Computer type
PC/Desktop
Computer Manufacturer/Model Number
Own build
OS
Windows 7x64 Home Premium SP1
CPU
Intel i7 2600k
Motherboard
ASUS P8Z68 Deluxe
Memory
G.Skill Ripjaws (DDR3-1600) 2x4GB
Graphics Card(s)
Nvidia GeForce GTS 450; Intel HD Graphics 3000(GT2+)