The CL3 will work, but I like to buy the CL 2 or 2.5 as it's faster and tends to be better quality. It's hard to find CL 2/2.5 right now. I'm not sure what's coming in the G5's from Apple, but it probably is the CL3. Search
http://www.ramseeker.com/ for some additional company's and possiblities. Crucial has some good things to look for in RAM with the links at the bottom of this page
http://www.crucial.com/store/listmodule.asp?module=DDR+PC3200&Attrib=Packag... however, they do ignore the CL 3 thing (at least as far as I remember) probably because they only sell that.
Tony!