Here are some benchmarks to show the differences between SATA3 hard drives and solid state hard drives for dedicated server applications.

The first benchmark is for web server performance the second benchmark is for database performance.

SATA3 Web Server Performance:

Source: http://www.storagereview.com/seagate_momentus_750gb_review_st9750420as

SSD Web Server Performance:

Source: http://www.storagereview.com/kingston_ssdnow_v_review_snvp325s2

Summary:
SSD Performance: From 1600 I/O to 4700 I/O
SATA3 Performance: From 60 I/O to 170 I/O

This benchmark is for database performance.
SATA3 Database Performance:

Source: http://www.storagereview.com/seagate_momentus_750gb_review_st9750420as

SSD Database Performance:

Source: http://www.storagereview.com/kingston_ssdnow_v_review_snvp325s2

Summary:
SSD Performance: From 1350 I/O to 3350 I/O
SATA3 Performance: From 60 I/O to 170 I/O