Iphoto and external hard drive

I have an iomega 1 tb hard drive which I have been using with my pc and have put all my photos on there with a view to only using my new iMac for photography. I can see the iomega hard drive in finder and can open photos from it in iPhoto but am unable to drag the iPhoto library to it to back up photos on my iMac (none of which are on my pc). Any ideas that will enable me to back up so my whole library of pc and iMac photos are on the same hard drive? Thanks

Try copying the iPhoto Library file with iPhoto closed. I think that may be the problem.

With that said, I strongly recommend that you dedicate an external hard drive to the iMac as a Time Machine backup drive. With this in place, you no longer have to worry about doing manual backups - and since Time Macine does constant, incremental backups, you can even restore individual revisions to your documents and data.

Nope, still doesn't work. I really wanted to have all my photos in one central place i.e on the hard drive. There is a "no entry" sign when I try to drag it across (don't know what else to call it - a circle with a line across which usually means you can't carry out the action you are attempting).