Just don't expect updated drivers from those manufacturers _unless_ they state at the download site that they support OS X 10.5 or higher.
The drivers that are built-in to Leopard will be good, at least for a few weeks/months, and newer than anything that you will find at the various web sites.
Epson is pretty good, and has a support page about Leopard, and the printers that are not yet supported are listed there as 'available for download soon'
http://www.epson.com/cgi-bin/Store/s...seBVCookie=yes