I have CUPS and my new printer (Epson Stylus C40UX, $49) working excellently 
on my RedHat 7.2 with KDE 2.2-11.  Without including all the mis-steps, this 
is what I did.

1. Made a directory called "CUPSStuff" off my home directory to put 
everything in

2. Downloaded these source packages from the location indicated

cups-1.1.12-source.tar.gz
http://www.cups.org/software.html

gimp-print-4.2.0.tar.gz
http://sourceforge.net/project/showfiles.php?group_id=1537

jpegsrc.v6b.tar.gz
libpng-1.0.6.tar.gz
tiff-v3.4-tar
zlib-1.1.3.tar.gz
ftp://ftp.easysw.com/pub/libraries

3. Unpackaged all these with Archiver

4. Did "./configure", "make" and "make install" in each source subdirectory 
for jpeg, tiff and zlib.

5. libpng does not use autoconf so it has it's own build rules.  It expects 
to see a directory called "zlib" with the zlib source on the same directory 
level as a directory called "libpng"  When the source packages are 
uncompressed, the sources are put in directories with names including version 
numbers.  Rather than change the directory names, I made symbolic links to 
the original directory names in my CUPSStuff directory, like this

ln -s zlib-1.1.3 zlib
ln -s libpng-1.0.6 libpng

6. Now, going into the libpng directory, I executed "make" and "make install" 
 Now with all the dependencies built, we can build CUPS.

7. First, I removed my LPD with "rpm -e lpd"

8. Changing to the CUPS source directory, I did the usual "./configure", 
"make" and "make install"

9. Start CUPS by issuing "/usr/sbin/cupsd"

10. To confirm that it is running, load it's web administration interface at 
http://localhost:631 in your favorite browser.  If it comes up, CUPS is 
running.  At this point I could print to my printer but not with full support 
since GIMP-PRINT is not installed yet.

11. I changed to the gimp-print directory to do the usual build process.  
However, to interface with CUPS, the configure command must have a special 
option specified.  I did "./configure --with-cups" then "make" and then "make 
install"

12. I restarted CUPS to "see" the gimp-print drivers with "/etc/init.d/cups 
restart"

13. Reloading the CUPS web administration interface in Konqueror, I installed 
my printer on the USB port, choosing the gimp driver.

Now, I have full access to hi-res printing and oodles of features offered by 
a $49 printer.  Sweet!

Along the way, I downloaded the KUPS package, a CUPS admin interface for use 
in KDE.  It compiled and supposedly installed OK (after downloading and 
installing QtCUPS library) but it seg faults when I run it.  I will have to 
look into that another time.  The CUPS web admin interface works fine for now.

There, it is off my chest.  I thought I would post this so that anyone 
wondering if a $49 Epson Stylus C40UX would work with Linux would know that 
it will.  And great!

Alan