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The aspx file extension is for Microsoft Net. See here:
http://filext.com/file-extension/ASPX
It indicates that DreamWeaver might be able to open them.
There is some hope, however because the above link does state:
ProgramName MIMEType
Active Server Page Extended
Found in Multiple GNU/Linux Packages
Found in Some FreeBSD/NetBSD Packages
Perhaps some heavy dogpiling might turn up some BSD apps that will workl