welcome to LQ forum.
for dual booting, first of all install windows in the primary partion of your hard drive.
After installing that, install Red hat in some primary or logical drive. And ofcourse have 200 mb of swap (its enough since you already have 256mb of main memory).
install the bootloader of Red hat in MBR.
Not at last install Solaris. Don't install its bootloader in MBR.
Now edit the /etc/grub.conf of /etc/lilo.conf file of red hat to make the entry for solaris.
before trying to dual boot your machine.