Have you tried to just run a generic computer performance tool on it. Most do a drive speed check.
Today, after a two weeks' holiday, I started to re-investigate the issue and made some interesting findings.
These are the drive's specs in OS X (10.6.8, clean install with updates), and as you can see AHCI seems to be enabled:
So, the SSD is not much of an improvement, and as the problems continue in OS X with AHCI enabled, this does seem like a hardware issue. Are my computers just too old for this drive? If yes, then what could be causing the dramatic speed difference between the Intel 320 and OCZ Vertex 2? Can the drive be faulty in that it works normally otherwise but just its read and write speeds are poor?
Look closely at the Link Speed and Negotiated Link Speed lines in your screen shot. Your controller is an Intel ICH7-M (mobile edition), and the ICH7 does not support SATA300 or SATA600. Your controller is SATA150 only; this is why you're seeing a "cap" of around 100MBytes/sec on your drive.
Yes, this must be it. Thank you. After the initial letdown I became too hung up on the benchmarks. Now that I've spent some more time actually using the SSD, It feels overall like an improvement over the HD, albeit not as visible as Vertex 2. I guess I'll just have to make do with the performance I get until I upgrade my laptop.