When I copy files to my WD 500 Gb FW hard drive the modification dates of the folders change to the current date. In contrast, when I copy files to an older Maxtor 250 Gb FW hard drive, the modification dates are retained. I would prefer to maintain the modification dates. Any advice on how to do this on the WD drive would be greatly appreciated.
This is just a guess, but they're probably formatted differently, since the brand of the drive would make ZERO difference. Maybe one is FAT32 (an older but common Windows format that the MacOS can also read and write to) and one is HFS+ (Mac-only, but superior to FAT32 otherwise)? Use Disk Utility to check. If that's not it, is there something else different about them? Maybe you added one to the Privacy list in Spotlight and not the other, or one is a USB2 drive and one a FW one (though I can't think of any reason that would make a difference).
Many thanks. The WD is FAT32. Can I change this to HFS+ without erasing and reformatting the entire drive?
Yep, I'm not aware of any software that'll convert from FAT to HFS+ (and to be honest, if such a beast existed, I probably wouldn't trust it with my data). Given that even if you COULD you'd want to have a full backup in case anything went wrong, you might as well just make a full backup somewhere, reformat it, and copy the data back over. Annoying, but safer.