This issue is addressed in KB:

Is there anyway we can run integrity checks on active/used databases for our website with SQL 2005 Std. Ed.? (SP2) We can't create a database snapshot to run DBCC CHECKDB against.

select @@version returns:

Microsoft SQL Server 2005 - 9.00.3042.00 (Intel X86)
Feb 9 2007 22:47:07
Copyright (c) 1988-2005 Microsoft Corporation
Standard Edition on Windows NT 5.2 (Build 3790: Service Pack 1)

Mark Havens