I wiped my computer, and now iTunes doesn't work. Does iTunes no longer work with Leopard, or did I do something wrong?

I wiped the computer using the original OS disk so I could give it to my mom in July. iTunes worked when I did it. I just updated the system and tried logging onto iTunes for the first time since I wiped the memory. I can log on, but nothing appears on the home screen. It looks like I can download files from the internet and import them into iTunes, but I can't access the stuff I've purchased from Apple. Is the iTunes Store no longer compatible with Leopard? Do I have to purchase a newer OS to access my purchases? Or did I do something wrong?