when insert rh first cd, when its to the point you can handle ur paritition, druid (or fdisk) will be able to read NTFS paritition and rest of the empy space.
btw, you said third parition hasn't been "format" yet, .... how did you do that? because by default, M$ will automatically format the entire harddisk, unless before u install M$, you used stuff such as partition magic to split'em....
anyway, linux will be able to read it, and just choose to install on the empty space, and you will be fine.
[the following msg is personal opinion, can disregard]
i think rd9 isn't as cool as all the previous redhat, u ain't get xine, mplayer, ur xmms can't play mp3 for legal reason, and so on ...
kde default is very slow unless u have to fine tune it
but that was just my 5 days redhat9 experience.