what programs can do echo for surround?

[E-Male]

i have a stereo track and i want to have an echo of it on the rears
i can do all mixing, but i haven't found i way to create an echo effect that does not include the original sound (seems like my tools are all still made for stereo)
do you know any program or plug-in that can do that?
(the cheaper the better, but please name anything that comes to your mind)

thx

[trapvector]

Hi There--Not sure if this will be helpful, but Audacity has an echo feature, and it's a free program. http://audacity.sourceforge.net/