"unixODBC-2.2.14" doesn't need g++-2.8 ( or libg++2.8 )
but will compile with the default gcc-c++-4.1.2 (4.1.1)
from RH EL5.
The text about "2.8" is for older versions (year 1999?),
AFAIK.
unixODBC-2.2.14 will even choose qt4 over qt3 if it is installed.
( If you need a GUI, else 'sh configure --without-gui' )
( I have build it on PCLinuxOS2007 )
'unixODBC-2.2.14.tar.gz'
: http://www.unixodbc.org/
# 'yum install unixODBC' will install version 2.2.11
on CentOS 5.2 = RH EL 5.2 so it is probably in your package
manager too.
Regards