Can't copy photos or music from external hd onto mac os x

[jgal]

I copied photos and music from windows xp onto an external hard drive and want to copy them onto my mac os x 10.5. for some reason it wont let me, says there is an error. i also can't delete any photos off the external hd. is there a way to copy photos into iphoto and music into itunes? i also can't put any files or folders from my mac onto the hard drive. is there a way???