<p>MySQL has this incredibly useful yet proprietary <code>REPLACE INTO</code> SQL Command. </p>

<p>Can this easily be emulated in SQL Server 2005?</p>

<p>Starting a new Transaction, doing a <code>Select()</code> and then either <code>UPDATE</code> or <code>INSERT</code> and <code>COMMIT</code> is always a little bit of a pain, especially when doing it in the application and therefore always keeping 2 versions of the statement.</p>

<p>I wonder if there is an easy and <strong>universal</strong> way to implement such a function into SQL Server 2005?</p>

The functionality you're looking for is traditionally called an UPSERT. Atleast knowing what it's called might help you find what you're looking for.
I don't think SQL Server 2005 has any great ways of doing this. 2008 introduces the MERGE statement that can be used to accomplish this as shown in:
http://www.databasejournal.com/features/mssql/article.php/3739131
or
http://blogs.conchango.com/davidportas/archive/2007/11/14/SQL-Server-2008-MERGE.aspx
Merge was available in the beta of 2005, but they removed it out in the final release.