Install Windows 8.1 on VMWare Workstation 8

1) VMWare Workstation 8 doesn't support Win 8 directly, so you may need some small tricks:

To keep it possible, I will note only two key steps:

a) Choose "I will install the operating system later."
b) Choose "Microsoft Windows" > "Windows 7".

Recomendations for better performance: Set the memory = about 1/2 of physical memory. Consider  enabling Virtulaization in host BIOS.

2) If you didn't allocate enough space for the VM, use Windows's DiskPart to extend the partition.

a) VM Settings > Hard Disk > Utilities > Extend...
b) In CMD prompt, C:\diskpart
    DISKPART> list volume
    DISKPART> select volume 2
    DISKPART> extend
    Check the space avaliable in C:\ drive.

Refer to "Extending partitions in Windows using DiskPart (1007266)" for details.