The Acer TravelMate TMP645-MG has an SSD storage medium which is better than the HDD storage medium found on most laptops of this age and type. 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.
This laptop's storage medium (SSD) is in fact the best storage medium across all notebook PCs of a comparable age and type to the TravelMate TMP645-MG.
The worst storage medium amongst comparable types of laptop is HDD.
If you want a portable PC with a better storage medium then you might want to consider the DELL XPS 13 ($1,652.41) (SSD).