The Thinkstation P500 has an SSD storage medium which is faster than the HDD storage medium found on most medium processor core computers that have been around for around the same time as it. Solid State Drives (SSD) store information in transistors on a circuit board rather than on optical or magnetic media. This has the advantage of being much faster than a traditional HDD drive.
An SSD storage medium is in fact the best storage speed across all medium processor core computers that are a comparable age to the Thinkstation P500.
An HDD storage medium is the worst storage speed amongst similar types of desktop computer.
If you would prefer a computer with a faster storage speed then you might also want to look at the Zotac ZBOX PI320 (Flash), or the Asus CHROMEBIT (£99.97) (Flash) which also has a higher rating.