Window 7 vs Window XP

[AngelGonzalez]

Does anyone has any compelling reason on using one over the other when developing SL applications?

Thanks

[AliMirzabeigi]

There shouldn't be. For more information please take a look at the following URLs:
- System Requirements tab in http://www.microsoft.com/getsilverlight/Get-Started/Install/Default.aspx
- http://www.microsoft.com/silverlight/faq/

[dotMorten_esri]

Only thing I can think of, is that if you also want to start developing Silverlight Apps for the Windows Phone 7 platform XP is not supported. (we'll have a beta version of the ArcGIS Silverlight API for WinPhone out very soon),