The ZBook 17 has a better storage medium than most portable PCs of this age and type. This notebook PC has an SSD storage medium, whereas most portable PCs of this age and type have an HDD storage medium. Solid State Drives (SSD) store data in semiconductors on a circuit board rather than using magnetic or optical media. Solid State Drives have no moving parts which makes them very fast and reliable.
An SSD storage medium is actually the best storage medium across all many processor core portable PCs that were released more than two years ago.
Across similar types of notebook PC the worst storage medium is HDD.
It may also be worth considering one of the alternative laptops that have an SSD storage media currently available including because of it's better review score, the U500VZ, or the U500VZ both from Asus.