How to make 2HDD as boot option?

Hi I have 2 hardisks,on one have implemented dual boot windows OS(WinXP and Win98)and on 2nd hardisk I have installed Linux now I want these two hardisk as my options for booting instead of the operating systems so that when I choose the 1st HDD I can boot into the windows and when I choose the 2nd HDD I can log into Linux…plzz advice thanx in advance..