Probably the timeout was not set during the install, or you set it to ")" by picking Windows as the default option to boot. Get into the file manager as superuser and navigate to the /etc/lilo.conf file. Right click and choose kate to open the file.
boot=/dev/hda
map=/boot/map
install=/boot/boot.b
prompt
timeout=50
message=/boot/message
lba32
default=linux
image=/boot/vmlinuz-2.4.0-0.43.6
label=linux
initrd=/boot/initrd-2.4.0-0.43.6.img
read-only
root=/dev/hda5
other=/dev/hda1
label=dos
Change the timeout value to 50 or 100 (5 or 10 seconds).
Then get into a terminal window, as superuser (or just get to the terminal window and type in su, then your root password).
Once there, type in /sbin/lilo and wait for the command to alter the bootloader (until you get back to a prompt).
On next boot, lilo should pause and allow you to choose Windows or RedHat.