The difference between linux and windows 2003 hosting

What's the difference between linux and windows 2003 hosting?

It depends on what you want from your web site. The Linux server will be more secure for your site. If you want to connect to a database you will need to learn a bit about MySQL (probably) and writing PHP web pages. The Windows server will be more prone to worms and malicious attack and you will need to learn MS SQL server and writing ASP web pages if you want to connect that to a database.
I prefer the Linux solution but others will tell you differently...