An iMac from 2007 (that had Tiger originally) would have had iLife '06. The next release was iLife '08.
iLife comes with new Macs, but the Mac OS X retail package does not have iLife included. So whatever version was previously installed remains installed. When you upgraded to Leopard, iLife '06 would have remained installed. When you upgrade to Snow Leopard, it should be the same thing. iLife '06 was out with the Intel Macs, so the individual apps should be
Universal apps (native with both PowerPC and Intel). When I search Google on the topic of compatibility (iLife '06 with Snow Leopard), I see some conflicting and inconclusive reports. But I can't see why iLife '06 should not work with Snow Leopard.
There are forum categories for the individual iLife apps, so you may get more detailed responses if you post a question in that area. You can see them from the main Discussions page
http://discussions.apple.com/index.jspa?categoryID=1