Nonetheless, it is important to remember that if you are planning to install SharePoint Server 2007 or Windows SharePoint Services 3.0, it has to be at least SP2, anything before that is not supported on Windows Server 2008 R2. SharePoint Team Blog: Install SharePoint Server 2007 on Windows Server 2008 R2

There was a bit of confusion/frustration raised over this topic, because WSS 3.0 slipstream with SP2 came out long ago (April 2009), but MOSS 2007 was for some reasons left behind, and MSDN subscribers saw slipstream SP2 edition only in January 2010.

WSS 3.0 with SP2:
x86: http://www.microsoft.com/downloads/details.aspx?FamilyId=EF93E453-75F1-45DF-8C6F-4565E8549C2A&displaylang=en
x64: http://www.microsoft.com/downloads/details.aspx?familyid=9FB41E51-CB03-4B47-B89A-396786492CBA&displaylang=en

MOSS 2007 with SP2 (trial):
x86: http://www.microsoft.com/downloads/details.aspx?FamilyID=2e6e5a9c-ebf6-4f7f-8467-f4de6bd6b831&displaylang=en
x64: http://www.microsoft.com/downloads/details.aspx?FamilyID=3015fde4-85f6-4cbc-812d-55701fbfb563&displaylang=en