LinuxQuestions.org - lots of confusion

hey all, i've been playing around with stuff and got a job as a helpdesk tech fixing windows all day and got hohesick, so i decided to install linux on one of my work computers at the desk. it's working pretty well and all, but i have a few questions. my system is setup as a dual boot on a 120GB drive:
C:\ 10 GB NTFS (XP SP2)
D:\ 50 GB NTFS (Windows data etc)
E:\ 5 GB FAT32 (for sharing data between OSes)
/ 10GB ext2 (Mandrake 10.1)
/swap 1 GB
/home ~20 GB ext2

the linux distro is mandrake 10.1. /boot is C:\ and i use Lilo . there is a partition between / and /swap that i want to put SuSE 9.1 on; now hopefully you know enough to help me out.

i want to install suse as a separate distro, not replace mandrake. i do want to use my existing /home for both distros; is this possible? in my experience with Linux, upgrading/changing distros doesn't require any changes to /home, so theoretically they can share it on one system since they're not on at the sametime. anyway. i tried installing suse to the space i made for it, twice. its default filesystem is reiser, but i chose ext2 to be consistent. what did i do wrong? the installer stops near the same time (after disc 1 is nearly finished, out of 5) each time i install. i know it's not the disc cause they're brand new discs. i've also tried with an iso of suse 9.0 personal that a friend had, and that did the same thing. can these two distros not play nice? is there something about SP2 or XP that won't agree with 3 OSes? i've had a Suse 9.1/XP SP2 system before using ext2, so i know it's possible for those two to exist. i think it may be the installer, as the distro itself is probably fine. is there a workaround? i'm not quite advanced enough to use a non-graphical installer on my system- i really can't afford to lose the functionality of my windows partitions.

now the next part of my question: although i use mandrake now, i do want to install suse on the computer. Mandrake's support of my motherboard, Abit AI7 is lacking to say the least. i recently updated my nvidia video drivers and now loopback doesn't initialize on boot. i don't understand what it is or why it doesn't load; it may not have anything to do with the drivers, that's just when i noticed it. anyway, i'm no longer able to get online using mandrake and i'm either going to reinstall it or suse over it. i'm not certain where lilo is stored and if i were to install suse over mandrake, if i choose to use lilo, will my system become unbootable? if i were to get both distros to install correctly, do i install a bootloader on the second or just modify the already existing one?

any answers or advice on this would be great, and if you need any more info from me, just ask and i'll tell you what i can.