I want to know how much space (in gigabytes) will a clean installation of windows 7 32 bit version take after installation.
After installing Windows 7 Professional 32-bit with all Windows Updates up to today (Includes .NET Framework) it took up about 31 GB hard disk space.
However, I have 8GB RAM. After running Disk Cleanup, deleting other installation files, and disabling Hibernation and the Page File, I freed up another 12 GB.
You're looking at about 20GB after some tweaking.
They say approximately 15GB - 20GB will acquire. Official document is here.