external drive problems

Its very likely that XP won't recognize it because it was formatted for OS/X using Mac OS Extended (Journaled) partition table. What you could do is split the drive into two partitions, one for OS/X and one for Windows.

Make half of it, or whatever storage capacity configurations you want, Mac OS Extended (Journaled) and the rest MS-DOS (FAT). OS/X will recognize both partitions and Windows will only see the MS-DOS (FAT) partition.

From the Disk Utility help file:

When you do the Add (+) in the steps above, you will choose MS-DOS (FAT) for one partition and then Mac OS Extended (Journaled) for the other. See attached screen capture.

WARNING: It is very important that you take any data currently on the drive and back it up on another drive before attempting to partition your drive. Partitioning will erase all data on the drive area you're working on.

 

Making a Windows readable format partition is one helpful resolution.
I'm not sure now adays but when I was using Windows on a different I was able to install the bootcamp drivers on the Windows machine and was able to see OSX formatted drives, if you have your Leopard install DVD you can try that, otherwise the partition scheme may be the better option for you.

 

You need HFS+ file system drivers for the Windows machine. You can read the drive using the free HFSExplorer found here. You'll likely have to pay for something like MacDrive if you want to be able to write to the drive from Windows. Alternately, you could share the drive on the network from your Mac, but that's more involved.

Paul