If you have little experience with linux it may be your easiest option to regain a working system, if you perform an upgrade install over your system, or simply fresh install if you don't have important files to lose.
If you'd like to work on fixing it, I'm sure many here will give you a hand, but it may be a slow process over forums. First step would probably be posting here your grub config from /etc/grub.conf (or if you've created a /boot partition it should be linked to /boot/grub/grub.conf).
also, use your cd to boot into rescue mode and retrieve the boot log from a failed kernel boot, do this right after you've tried to boot into a kernel that recently worked. The boot log should be at /var/log/boot.log.
If you retrieve that log, also retrieve the XFree86 log at /var/log/XFree86.0.log and post them here. It is really impossible for anyone on a forum to help you much without access to those logs.