I want to have 2 OS installed on my HDD (80GB).
I installed Windows 7 first.
Then booting from the DVD drive I launch the RHEL setup and in the partitioning phase I get the following errors:
Windows 7 and Linux can be installed on a 80 GB drive.
I would shrink Windows 7 partition to say 60 GB. So in the 20 GB left Linux can be installed.
To shrink Windows 7 partition you can use Disk Management - click on Start, Run: diskmgmt.msc Right click on Windows 7 partition and select "Shrink Volume"
When installing Linux you have two options:
How big is your Windows partition? If your Windows partition consumes the entire HDD, then you're going to need to shorten it and create free space on your hard disk first. Once you've done that, you should be able to direct the RHEL install to use the free space.
Also, 80GB is barely enough space for a Windows 7 install. If you want a dual-boot system, then you're going to need a larger hard drive. I dual-boot Windows 7 and Ubuntu on a 160GB system, and I'm pressed for space.