If your server support it, try to get into the BIOS and create a Volume around 50 GBs  to install ESXi then you can either use the rest of the space for local storage or attached SAN/NAS shared storage. ESXi generally requires a GPT-based disk, so if at any point during your changes/reimages, the disk format type was changed to MBR, there's a potential of running into problems. Also, ESXi doesn't play nice with software-based and fake RAID, so make sure those are disabled in the BIOS if that's an option. VMware removed driver support not only for some commodity network cards, but also for lots of SATA controllers that have never been on Hardware Compatibility List (HCL).

Raul.

VMware VDI Administrator

http://ITCloudStream.com/