This is a good idea, and a very easy install for any membername website, not just Deviant Art.
You could simplify the whole process even more as well. Instead of entering their DA info as "bratzer.deviantart.com", you could have them simply add their DA username, or just "bratzer". Then, change your template info to:
Code:
<!-- Deviantart start -->
<if condition="$post[fieldX]"><a href="http://$post[fieldX].deviantart.com" target="_blank">
<img src="images/misc/DA.gif" border="0" alt="View my DeviantArt Profile!"></a>
</if>
<!-- Deviantart end -->
chkdgate, yes you can easily get it to open in the same window by removing
target="_blank" out of the URL in the template addition above.