Unable to make more than four partitions with the Windows 7 installer

I'm setting up a multi-boot system. It has a 1,500 GB hard drive, which I would like to split into fifteen 100 GB partitions. There are immediate plans to use eight of the partitions for various OS installations. The other seven will be for future use.

The problem is that the Windows 7 (Professional 32-bit) installer only allows me to setup the first four partitions:

Disk 0 Partition 1: System Reserved  100.0 MB  System    
Disk 0 Partition 2                    99.9 GB  Primary
Disk 0 Partition 3                   100.0 GB  Primary
Disk 0 Partition 4                   100.0 GB  Primary
Disk 0 Unallocated Space            1097.3 GB

Partition 1 was made automatically by the installer when I allocated the first 100 GB.

How can I make the other partitions? Do I need to use the 64-bit Windows 7 installer, or do I have to use some third-party software?

If I recall correctly, you can only have a total of 4 partitions on a disk due to master boot record limitations. You'll need to create an extended partition, and start creating logical partitions inside of that, for OSs that support booting from logical partitions.