First, check and see how much you have compiled as modules. If you want to save a lot of space, compile what you can as modules instead of compiling them directly into the kernel.
Second, if your kernel is too big, that's okay!
Well, that is, if you are booting off the harddrive. If you are scared to replace your boot sector, just simply create a Mandrake 9.1 cd 1 disc. I personally use Debian, but I keep this 'bad boy' around to easily resize my partictions (including NTFS) and to reinstall the Windows boot sector if I have to (I also keep a Debian 'Woody' Disc 1 around in order to start up a shell so I can go in and fix things instead of reinstalling the Windows boot sector). Don't worry, as long as you compiled your kernel right, LILO and Grub should work just fine. I personally use LILO and enjoy it's flexibilty.
Anyway, if this helps, just post a reply so that people who google and find this post will know if it did or did not work.