Hi, The easies (though perhaps not most elegant) way to prevent this in the future is to move your modules directory befor the make modules_install, tar up the modules directory from the build then move your old modules back.
Your probably going to need to either use the kernel you build or if that's not possible rebuild the kernel on your laptop. The "official" Debian way is to use make-kpkg to do the kernel build which will create a .deb of the new kernel and modules. Very cool and works well for lots of folks. Personally I've built alot of kernels, but have never got kpkg to behave. Probably because I can build a kernel without it and thus haven't spent the time to really learn how to use this tool. -Jon