new kernel problem

["Daniel Smith" <danielaksmith@gmail.com>]

I've compiled a new kernel, same version as the old one, and installed
it using make-kpackage.  When I try to boot it, however, it says it
can't mount my filesystem, and it freezes.  I am booting from
reiserfs.  I thought it might need an initrd, so I pointed it at my
old initrd.  It told me it couldn't find /lib/modules/2.6.18, so I
opened up the initrd using cpio and moved /lib/modules/2.6.18-4-amd64
(the old kernel name) /lib/modules/2.6.18 to match the new one, put it
all back it, and it got farther in the boot sequence but it still
didn't come up.  I am wondering how I can automatically make an initrd
to match my new kernel (the old initrd was automatically installed
when I put debian on) or any other way I can make it work?

The only reason I need a new kernel is because when I compile modules
and try to install them it says:
FATAL: Error inserting ndiswrapper
(/lib/modules/2.6.18-4-amd64/misc/ndiswrapper.ko): Invalid module
format.
so alternately, is there a way to get the sources(/headers) that match
my kernel so I  can compile the module properly to match my kernel?
This would alleviate the need for a new kernel altogether.

Thank you muchly for any help.