I have heard some confusions on this recently and wanted to post this for generic reference.

You can install SharePoint 2007 connecting to SQL 2008 R2 as long as you have SP2 for SharePoint 2007 or later CU installed.

Ref: (scroll down to software requirements under Server Farm Installation requirement >> Database server)

http://technet.microsoft.com/en-us/library/cc262485(office.12).aspx

 Hope this helps.

 

Cheers,

Priyo