Went to that site, they recommend OMNI version .7+ and RH7 comes with pre-.5.x. 
  Guess you might want to upgrade to either a newer version of Omni, or better 
yet, upgrade RH to 8.0 as it comes with .7.x

http://www.rpmfind.net/linux/rpm2html/search.php?query=omni&submit=Search+...&system=redhat&arch=

> I don't know if I need an intro to linux printing or just a push in the 
> right direction in getting this setup correctly.  I've tried RTFM'ing 
> (till my eyes are sore and several linux books strewn about my desk:)
> 
> RedHat 7
> Epson Stylus Photo 820.
> 
> www.linuxprinting.org/show_printer.cgi?recnum=Epson-Stylus_Photo_820
> 
> says that this is supported and the recommended driver is gimp-print but 
> does not give any directions on how to use it.
> 
> When I use printtool and test direct to port, I get one line that says 
> "This text should appear on the printer on /dev/lp0".
> When I try ASCII test or PostScript test page I get many pages of random 
> characters.
> 
> I've got the Epson Stypus Color 800 (which is the closest I found usint 
> Printtool).
> 
> Can someone either give me a quick rundown on what I need to do or where 
> I can find good step-by-step directions to get this working?
> 
> My next question will probably be getting my remaining Windows pc's to 
> print on this printer.