Determining the Size of a Site Collection

Problem: You may need to determine the size of a site collection.  In my case I need to move a SP2007 site collection that is a content database with multiple other site collections.  I need to know where to put the site collection data on my SP2010 test environment. 

PowerShell for SP2010 sizing:
$used = (Get-SPSiteAdministration -Identity ).DiskUsed
Move the site collection using Move-SPSite -DestinationDatabase

Stsadm cmd for MOSS Site collection size:
stsadm -o enumsites -url http://url 
More Info:
http://technet.microsoft.com/en-us/library/cc825328.aspx
http://www.toddklindt.com/blog/Lists/Posts/Post.aspx?ID=270