I normally replace line breaks with the HTML equivelant, which is <br />. This will retain the line breaks when the data is displayed on an HTML page. If you want to display the data in a text field again, you need to re-replace the <br /> elements with vbCrLf.
'| Replace line breaks with <br />
Dim strContent: strContent = Replace(Request.Form("yourData"), vbCrLf, "<br />")