The Acer TravelMate TMP645-M has an SSD storage medium which is better than most laptops that have been available for around the same time as it. Most medium processor core laptops that were released more than two years ago 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 in fact the best storage medium across all medium processor core laptops that have been available for a comparable time to the TravelMate TMP645-M.
An HDD storage medium is the worst storage medium amongst similar types of laptop.
If you are looking for a notebook PC with a better storage medium then you might want to consider the DELL XPS 13 (SSD).