If you are dealing with a 64-bit print server and are looking for 32-bit drivers, this post is for you. Also works if you are on x64 clients and want to add the driver to a 32-bit server (SBS 2003 for example).
Check out the Official SBS Team Blog’s post for screen shots and the full text.
Short version, is browse to the server from your 32-bit client PC while logged in with an account that has server admin rights, select the printers and faxes share, and then server properties from the file menu. Drivers tab, then add. You’ll have it from there, or jump over to the SBS blog for screen snips and more details.