>>Can you show your statement? This error message means that TEXT type can not be used for exact match. Varchar field can and should be used.
>
>Ok, now I am confused. I did the same test again and did not get the error this time. So, on this second simulation, searching for exact value on a VarChar(10) field worked. So, this brings it down to using VarChar(100), assuming 100 characters would be the maximum to support, and would save a bunch of disk space on the database because the first 26 million records won't be affected and for the upcoming ones which would be empty or containing not that much characters. This is as good as long as I do not need the unicode support.
>
>Thanks

In SQL 2008 I suggest to also look into row and page compression. Check
http://blogs.lessthandot.com/index.php/DataMgmt/DBAdmin/compressing-data-with-uniqueidentifier-columns (this blog also touches the general idea of compression).