i dont understand why is everyone talking abt 3rd party softwares. @vimal, why think of spending money while xp has everything that u need? start your pc with a 98 boot disk & install 98 on D. when u r done, u'll see your xp/dual boot is gone. this is 'cos 98 has overwritten the master boot record. dont panic, ur xp is safe in C. now boot ur pc with an xp boot disk & when that 1st blue screen comes, press R to enter recovery console. it'll ask which os u wanna log in, for u its 'C:\windows'. then it'll ask for an acount name & pass from ur xp acounts. log in as admin, type 'bootcfg /scan'. it'll scan all ur current windows installations. u'll find 2 windows, i guess, 1 is D windows & 1 is C windows. then type 'bootcfg/ rebuild'. now it'll say sthing like
[1]c:\windows
add to boot(y/n)? y
enter load identifier(some name for this os) XP(in ur case)
enter load option(is it default or not) /fastdetect(if u want xp to be ed automatically, else just press enter)
[2]d:\windows
enter............... y
enter............... 98
enter............... /fastdetect(if u want 98 to be default)
restart ur pc & voila! u got the dual boot os choose screen, & none of ur os has been harmed.
thats all! see, no need to buy expensive 3rd party softwares.
hope it works for u.
good luck