I believe your 120gb is a 2E. Unless its a Vertex and not Vertex 2, it would have a lower read/write and different controller (indilinx) if so
Read: Up to 250 MB/s
Write: Up to 180MB/s
Sustained Write: Up to 100MB/s
Whats the product code? I could be absolutely wrong, just don't remember a 120gb plain 2.