The following vb.net function will format the date-time  to pubDate format for rss 2

Private Function BuildPubDate(ByVal d As Date) As String
Try
Dim RV As String
Dim day As String = d.Day.ToString
If day.Length = 1 Then day = "0" & day
Dim month As String = d.Month.ToString
Select Case month
Case "1"
month = "January"
Case "2"
month = "February"
Case "3"
month = "March"
Case "4"
month = "April"
Case "5"
month = "May"
Case "6"
month = "June"
Case "7"
month = "July"
Case "8"
month = "August"
Case "9"
month = "September"
Case "10"
month = "October"
Case "11"
month = "November"
Case "12"
month = "December"
End Select

Dim Mtime As String = ""
Dim mDate As Date = d.ToUniversalTime
If mDate.Hour.ToString.Length = 1 Then
Mtime = "0" & mDate.Hour.ToString
Else
Mtime = mDate.Hour.ToString
End If
Mtime += ":"
If mDate.Minute.ToString.Length = 1 Then
Mtime += "0" & mDate.Minute.ToString
Else
Mtime += mDate.Minute.ToString
End If
Mtime += ":"
If mDate.Second.ToString.Length = 1 Then
Mtime += "0" & mDate.Second.ToString
Else
Mtime += mDate.Second.ToString
End If

RV = d.DayOfWeek.ToString.Substring(0, 3)
RV += ", " & day & " " & month.Substring(0, 3)
RV += " " & d.Year.ToString & " " & Mtime & " GMT"
Return RV
Catch ex As Exception
Return ""
End Try