Checking to see how many sites are in a collection

We have about 450 employees and have noticed some performance problems in SharePoint. The company that set up our portal for us recommended one site collection for ease of maintenance, but I suspect we may have exceeded the 200 site barrier. Is there an easy way to check and see how many sites are in the collection (or does it have to be done programmatically)?

You will need to write a little PowerShell script or command program to do this.