Any disadvantages of Silverlight

silverlight-2.0

We are planning to develop a web based application using Silverlight 2.0. The application will be used by our company employees. The application will be accessed using IE6 (Yeah IE6) and Silverlight is not installed.

We will be rolling our Silverlight through our IT support to all the users. All employees use Windows.

Is there any thing else which I should consider before developing this application using Silverlight.

Are there any disadvantages?
Will there be any performance issues in IE6? Should I upgrade to IE7/IE8?

This application will be used by business who open 10's of spread sheets and applications. 512MB is the standard memory available for an employee's PC. Will it be heavy to use Silverlight in IE6? Will it cause the system to hang?

Any other points I should consider?

Edit: After the first answer from Mark. Are there any "stress test" app available to check our users PC build?
Thanks in advance.

Best Solution

One issue to consider is that Silverlight is still a very new technology, with a few bugs to iron out (search SO for the silverlight tag to find a couple - list box resizing is one of the most egregious).

I haven't used Silverlight 3 yet so I don't know how many have been resolved but just be aware that you'll likely have to put in a number of hacks/workarounds in the near future.

Also Silverlight is on the heavyweight side of web frameworks and if your clients are on more restrictive hardware and software and ASP.NET / AJAX solution might be more appropriate. Maybe try building a 'stress test' Silverlight app (with lots of controls and frequent server trips) to see if the performance hit is too great.