If you are careful during the install, you should have no problems. Before you start tho, be sure you have some free space for the linux partitions. You will need 2 partitions, a swap partition, usually sized a 2x the installed ram, but 512meg to 1 gig is fine. And the OS partition, at least 10 gig if you really plan on using this. A basic suse install is about 2.5 gig with open office and some additional apps installed, I have run a full install on 5gig, but only had .5 gig free. (that was a "install everything" install, not recommended for most people).
Now, you can either use the partitioning utility of your choice, ie partition magic, or you can just go to the storage function in computer administration in xp to shrink your present partition down to leave whatever free space you would like.
When you start the suse install, it will examin your system and decide where it thinks it should install.
Linux does not use letters for drives, it uses numbers.
it also uses differrent designations for IDE harddrives(hda#) and SCSI harddrives(sda#).
Assuming an ide system:
The first physical harddrive is hda, the second harddrive is hdb.
If you have a drive now partitioned as one partition, it would be hda1. If you had it partitioned as 2 primary partitions, they would be hda1 and hda2.
If you had 1 primary partition and one logical partition, it would be hda1 and hda5.
Hope you can follow that, because you need to understand where you are going to put things
This can really get lengthy, and I hope our hosts here don;t mind, but if you want to see what the screens look like, and some detailed information, I did write an advanced install tutorial for suse 9.2 pro, and 9.3 is the same screens. This may give you an idea of what you will be seeing, and what you will want to do, altho not all this is necessary for a simple 2 os system, a pictuer is worth a thousand words.
http://www.bitbenderforums.com/vb22/showthread.php?s=&threadid=66029