Well that drive was £400
I had a 500gb 7200rpm drive in before that. I can guarantee you that SSD will wipe the floor with any HDD.
The guy obviously doesn't know what he is talking about. Ask him to show you a HDD that will Saturate a SATA II connection. This SSD won't perform at its stated speed as it is SATA III (but backwards compatible). It's capable of read speeds of 550mb/sec and 520mb/sec write speed. I'm my MBP with SATA II it will perform at around 285mb/sec for both. Still way way faster than any HDD