iLife doesn't come with Leopard. It is just bundled with new iMacs. Did you get your iMac with Leopard preinstalled or with Tiger and then you upgraded it to Leopard ?
Not sure what's the deal with new systems with Leopard preinstalled, but I know that when I bought my iMac with Tiger, I also got 2 disks with OS X and some utilities and among them, iLife.
If you have those disks, just browse through the folders and search for iLife applications. That's what I did when I installed Leopard and everything works great... actually the only problem I had was with iMovie because it wouldn't start, but the next day I downloaded some updates and among them there was iMovie update... now everything works perfectly.
How's your new iMac ? Noticed any display problems so far (hope not) ?