The DELL Precision T5810 has an SSD storage medium which is faster than the HDD storage medium found on most comparable spec desktop computers that were released 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 actually the best storage speed amongst all personal computers that have been on the market for more than two years.
An HDD storage medium is the worst storage speed across similar types of PC.
It may also be worth considering one of the alternative SSD computers currently available including because of it's better review score, the DELL Precision T1700 SFF (£600.28).