Do be sure to back up anything really important. I have had zero problem installs, and once I lost everything in Win and had to start over. Your first time it's easy to make mistake.
Since you are FAT 32, it seems likely you are not XP. Do be aware that XP defrag does not COMPRESS all HD contents to front of HD, as Win 98 did. So, it is possible to think you are compacted and that 15GB are free, when they are not.
I think virtually all distros can read Fat 32 partitions. It will be necessary to mount them if the distro does not do so by itself.
I have CentOs, I think 4.3, on an old Compaq, 400MHZ with 20GB HD, multiple booting not only with Win98, but also one or two other distros. The only one that can't see anything else is Win... There is a file explore2fs that installs in Win and lets you take one file at a time FROM linux.
I use it all the time on XP, and Mandriva and others usually will READ Win okay.