Comment 12 for bug 243930

Through the Synaptic Package Manager, I enabled the "hardy-backports" repository and was able to remove the 2.6.24-19 modules to install the 2.6.24-18.41 modules and it worked for me (granted, I'm on a 64-bit rather than a 32-bit).

Either way, if you aren't seeing more than one version of the restricted modules, make sure you have the backports repository enabled.