I just bought a Mac, have always been a PC person. Arrghhh, I should have stuck with PCs!!!! Much less hassle. Stupid me. But so be it, too late. Okay, so my new mac (MacBook Air with expensive SSD drive, only 128 gig) has a much smaller hard drive than my old PC (ancient and well-used and slowly breaking Acer TravelMate with 256 gig), so I bought a Seagate external hard drive on which to store my very extensive photo collection so I wouldn't need such a big hard drive in my computer, and also to use to back up my new Mac from time to time. The instructions on my drive said that if I wanted to use it on Mac and PC I should not follow their formatting system, so I didn't. I copied tons of files onto the drive and transferred them onto my new mac. Then copied tons of other files from my PC - my photo collection - and didn't transfer them, since there isn't space. Also loaded a bunch of videos and stuff onto the external drive. Now I discover that I apparently can't actually write on the external drive with the mac. Which means it is useless as a backup. And I can't download future photos onto the external drive. (I also can't figure out how to download them onto the mac at all, and haven't found a freeware photoshop clone for the mac, but those are separate problems.) Is there anything I can do about this? Especially anything I can do about it without having to reformat the external drive and then re-back-up everything that I've already stored on it (the photos & videos)? I always knew macs were a *&%^$ pain! I should have just gone with the much cheaper and slightly lighter Toshiba ultrabook, and figured I'd get used to the crummy keyboard... Grrrrrrr. But okay, what's done is done, no use crying over spilt milk, and I realize I am asking these questions of people who think macs are the greatest thing since sliced bread! So I guess I should keep my opinions to myself. And also thank the folks who provide info in these discussions - I've gotten tons of useful info here already, which I greatly appreciate.