Hmm.. I'd recommend the Arctic Silver III thermal compound - I don't know if it also comes in the Antec name, but this is the first I've heard of this "co-branding" - I thought Arctic Silver's website says that there are several imitation arctic silver out there, and that might apply to the "Antec Silver". I might be behind in the news on this thermal compound thing, but since I'm already using the AS III on my cpu, why should I worry?
If you don't really care about the brand names, it's a thermal compound after all - it should work almost the same way.