If your site is getting big and you want a better
domain name, yes, you should pay for a web hosting
company to get better service.

I signed up http://www.your-site.com/ earlier,
it's one of the most cheapest web hosting company
that I found.  It costs $60 to host per year with 
50MB disk space, and $20 for getting your own 
domain name.  Transfer speed is decent too. 
This is a very good deal, one of your cels 
probably costs more than $60 :)  I don't like
those xoom or geocities too, I hate those banners.