i'm not absoluely sure you wanna do. you can boot your machine ev. with a floppy and tell the kernel to get the root-filesystem via nfs from another box in your network. there are pretty howtos how to do that at www.tldp.org
or allready on your system (think nfs-boot-howto, x-terminal-howto, ..or similar).
you can tell your kernel via parameters where to find the rootfs, assign ipaddress,...
your kernel needs to support rootfs via nfs. for swapping over nfs there are network block devices need to be enabled on both sides (<- have never tried that).
if there is a cdrom in your machine and it's bootable you may also choose to build a bootable cdrom from your current sys to have a working (emergency) cdrom. i think the package is called "bootcd" on debian. (beware - i finally got it working, but it took me several tries - think it's just beta).