For mutiple booting options I would suggest that you install GRUB(GRand Unified Bootloader) ; its the best one i have ever used by now. I have also got win xp runing on my box with redhat linux7.3; so i use GRUB for multiple boot options...like its more userfriendly than lilo ... thats what i fell...u get a nice screen when start up ur box & u can choose whether to start win xp or linux. If u don't have grub in your SuSe8.0 installation cd; then you that download GRUb from
http://www.gnu.org/software/grub/grub-download.html
GRUB Compatibility: booting FreeBSD, NetBSD, OpenBSD, and GNU/Linux. Proprietary OS's such as Windows 9x/NT/2000/XP, and OS/2 are supported via a chain-loading function.
For your second problem...you have not mentioned what you need to be fixed with the hardrive; i presume if you want to merge the 20/10 gig partitions you can use Partition Magic
7.0(
http://www.powerquest.com/partitionmagic/) or even windows MS-DOS FDISK will also do the same but you need to know how to use FDISK. Attach your 30gig hardisk...boot to winXP...goto mSdos command prompt; type fdisk & press enter. You may use FDISK help for useful partioning commands. I hope so this solves your problem.