XBAPs work with the 64-bit version of Internet Explorer, which is great. However, IE7's Useragent string does not indicate that .NET 3.0 is installed on the system. Here are the UserAgent strings on my machine (Windows Server 2003 x64):

IE 32-bit:
Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.2; WOW64; .NET CLR 2.0.50727; .NET CLR 3.0.04506.30; .NET CLR 1.1.4322)

IE 64-bit:
Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.2; Win64; x64; .NET CLR 2.0.50727)

So how can I determine whether 64-bit IE is compatible with an XBAP

- Imad

Re: Windows Presentation Foundation (WPF) 64-bit Internet Explorer and XBAPs

Chango V. - MSFT

Yes, we've missed the 64-bit case. We'll try to correct this as soon as possible, hopefully with SP1.

Unfortunately, we can't recommend any easy alternate way to detect the framework. But if you are determined, it's feasible:
- Use an ActiveX control. The control could set a cookie or expose a minimal scripting interface...
- Similarly, use a WinForms control (activated in an HTML page as shown here)...