I am working on an ASP.Net web application that must print dynamically created labels on standard Avery-style label sheets (one particular size, so only one overall layout).
I just went through the same thing. Ended up switching and making a short little JSF app (running on Glassfish) that uses JasperReports to print directly to the lable printer. Push button, instant label at the printer, don't even have to view it on-screen if you don't want to since Jasper can directly output to printer (as well as PDF in browser).