Logic check and/or better way?

[Rocketdawg]

Hate to be paranoid, but....

I wrote a function that takes the height and width of a full size, uploaded image and returns - allegedly, It seems to anyway - new dimensions with the aspect ratio preserved.

My function seems awkward. Could anyone suggest a better approach?
Thanks!

Function RetainAspectRatio(ByVal imgHeight As Integer, ByVal imgWidth As Integer, ByVal IsItASmallThumb As Boolean) As ArrayList
        Dim blnSizeCheck As Boolean = IsItASmallThumb
        Dim maxheight As Integer
        Dim maxwidth As Integer
        If blnSizeCheck Then
            maxheight = 93
            maxwidth = 125
        Else
            maxheight = 300
            maxwidth = 400
        End If
        imgHeight = Convert.ToDouble(imgHeight)
        imgWidth = Convert.ToDouble(imgWidth)
        'Get the new height and width depending on whether the end result will be a small thumb or medium-size image
        'image
        If (imgWidth > imgHeight) Or (imgWidth = imgHeight) Then
            While imgWidth > maxwidth
                imgWidth = Math.Round(imgWidth - (imgWidth * 0.01), 0)
                imgHeight = Math.Round(imgHeight - (imgHeight * 0.01), 0)
            End While
        ElseIf imgHeight > imgWidth Then
            While (imgHeight > maxheight) Or (imgWidth > maxwidth)
                imgWidth = Math.Round(imgWidth - (imgWidth * 0.01), 0)
                imgHeight = Math.Round(imgHeight - (imgHeight * 0.01), 0)
            End While
        End If
        'send the new dimensions back in an arraylist
        imgWidth = Convert.ToInt32(imgWidth)
        imgHeight = Convert.ToInt32(imgHeight)
        Dim arDimensions As New ArrayList
        arDimensions.Add(imgWidth)
        arDimensions.Add(imgHeight)
        Return arDimensions
    End Function