Depends on how long you want to wait, Jane! Also, there should be new iMacs along some time soon...the typical cycle is about 8-11 months and the last ones came out in April 2008. Unless they go much longer between new models than usual, they'll come out before Snow Leopard.
Since iLife comes with an iMac, I wouldn't buy it for your machine now - but if you want to load it on your husband's and are planning on bestowing this iMac (if it's still working!) on a family member, then that's another consideration.