We have an existing POS system that faithfully records financial data into an SQL database. The system doesn't have much in the way of reporting, so we've implemented our own system. Simply put, we denormalise the financial data into a large table. We then connect an Excel spreadsheet pivot table to this large table. We suck the data in, use the pivot table to slice and dice it and total up the figures. We then create charts in Excel of the data. This works very well and the charts have proved very useful.

We'd like to make these charts available on our intranet website. Rather than have everyone download the large spreadsheet and play with it, we just want the charts on a few pages.

I'm sure there are many ways of doing this. Our contraints are:

* The raw data is in SQL Server 2005 (under MS Windows Server 2003). This is a production database connected to our POS terminals, so we must not add significant load to it.
* Our intranet site is drupal-based and we have some PHP knowledge so we could write a drupal module and use a PHP charting library.
* We have some C# / Visual Studio knowledge.
* We have good SQL knowledge so we can further manipulate the data within SQL Server. This can be done as a batch job out of hours to minimise the load on the server.
* Overall, we have limited development time and capability

Given our contraints, can I have some suggestions as to a simple-to-implement design for a system to display the charts on our website. No need for great detail, just some pointers in the right direction for further research.