Hello, My grandparents have OS X Tiger and want to upgrade to Leopard. If they purchase this item on eBay, would it be compatible? What I mean to say, the description says 10.5 to 10.6 not 10.4 to 10.6, so can a Tiger user upgrade with the "Snow leopard upgrade" or do they have to get a different version? Like a full retail version? Is the only difference that on Apple.com, Leopard users only have to pay 30 over the full price, or are there different versions and different CD's? http://cgi.ebay.com/MAC-OS-X-10-5-t...3a525e445c&_trksid=p3286.c0.m14#ht_1387wt_986 Thanks so much!