Print Servers - Compatability with Printers

I purchased two Viewsonic 802.11g Print Servers.

I set both up on my wireless network. I was able to get my Canon i470 color
printer to work with both servers. They both work properly in wireless mode
with this printer.

I have an HP Laserjet 1000 and an Epson P700 and I can't get either of these
to work properly. The Epson hangs up during printing and the HP Laserjet
doesn't do anything.

When I call Viewsonic (their tech support people suck!) I get many excuses
but no solutions. All printers are USB, and all less than 2 years old.

Any ideas what I might try?

Thanks in advance.