Make sure your drive isn't in PIO mode. If it is, you need to run it in DMA. I can't see any other reason why the drive is performing so slowly. What motherboard have you got Conrad11 and what is your SATA controller. Usually, in devce manager under the IDE/ATAPI controllers, you have an option in the properties to let BIOS set the transfer rate, then you have to go into BIO and make sure everything is setup on Auto for the drives.
About this debate on modern drives - it entirely depends on the platters used/size of the drive. An 80GB modern drive will get about 51MB/s (I got my Hitachi 7K80's SATA-II's in Feb and they got that. Larger drives have larger platters usually and these are necessarily denser than the smaller drives. This means they have a slight advantage due to their sheer size. My 1 year old Seagate 7200.8 250GB scored 59.8MB/s (no HDtach, sorry). TBH, I think 62MB/s is about the limit for a 7200rpm drive, even one using large platters - my Seagate uses two 133GB platters which are among the fastest, however Seagate's aren't fast drives, hence the reason it topped out where it did. In a faster drive like the Hitachi, it might have scored higher. For reference, my Raptor 74GB's scored about 66MB/s-70MB/s and the 150GB I had 78MB/s.
james.miller is right, there has been a trend in increased speed, but I think we've finally hit the wall for 7200rpm at about 62MB/s (max). This does depend on the controller too though. Often Intel ICH6R and 7R score consistently higher than most other controllers - one thing I'll give Intel
.