Dymo Label Printers have posted a useful page of information covering the use of the old labelwriters with Vista and Windows 7.

As previously reported here the Dymo Labelwriter 310 driver for Windows 7 & Vista does not support all of the 300 series printers. Dymo Label Printers have proposed a few solutions, but rather than repeat them here you can read them for yourself:

Solutions for unsupported labelwriters with Windows 7 & Vista