Normally, I would use a PHP webservice to do this, but since the front-end is hosted on a linux box, I need another way to do this (so I don't have to go through the trouble of installing FreeTDS, etc. I will if I have to).
Is there a better way to do this? I'm not a web guy, but I'm trying my best.
Not really - especialyl given that for security reasons silverlight apps should only connect back to the host they were loaded from (otherwise a silverlight app could be abused as network scanner etc.).
If the web host is a linux box then you will have to write a web service as a go between for Silverlight and SQL Server. If you have an ASP.NET capable web host available you can host the Silverlight in a RIA Services project, which gives you more direct access (still not actually direct, but you treat it very similarly).