Gentoo and WinXP

Hi, I recently installed Gentoo to be dual-booted with XP.  I installed 
Gentoo first and got it to work just fine.  After a few days of playing 
around in it, getting settings to my liking, etc, I installed XP.  To my 
disappointment, after installing XP, Gentoo wouldn't boot at all. 
 Unfortunately, I don't remember the error and have since I reformatted 
everything, but it seemed as though installing XP screwed up the TOC. 
 Now, this seemed odd to me because, with Mandrake, I would reinstall XP 
multiple times (Windows needs that you know :-\) and it would never 
cause any problems to Linux.  So, my question is has anyone else 
experienced trouble dual-booting?  Has anyone tried reinstalling XP 
after Gentoo was installed?  I ask especially because I reinstall 
Windows every 4 months or so and I'm hoping I won't have to reinstall 
Gentoo sop often as well :-\

Thanks in advance!
Brian

-- 
"He who joyfully marches to music in rank and file has already earned my contempt. He has been given a large brain by mistake, since for him the spinal cord would fully suffice. This disgrace to civilization should be done away with at once. Heroism at command, senseless brutality, and all the loathsome nonsense that goes by the name of patriotism, how violently I hate all this, how despicable and ignoble war is; I would rather be torn to shreds than be part of so base an action! It is my conviction that killing under the cloak of war is nothing but an act of murder."

-- Albert Einstein (1875-1955), German-born American theoretical physicist, theories of relativity, philosopher