dual boot linux?

[mike enriquez]

I am a newbie on this subject. I am having problems setting up a dual
boot with xp and linux. 
I have done this before and no problems. But on 300 gig HD I am having
problems with Red Hat & Suse. I installed xp first then I install Linux
and my computer will not boot. I use the xp cd to repair the master boot
record but this wipes out the linux set up. Both time Linux did not take
me to the Grub setup as it generally does on good installs.
I had my dual boot on an 80gig HD so I purchased a new 300 gig HD to set
up the dual boot but I am stuck. 
I installed RH by itself and the install works fine. 
Does anyone out there have any ideas.
Thanks
Mike Enriquez