So basically, your boot loader isn't launching?
Does WinXP start?
Do you get a No System Disk error?
I believe that during the install, you get the option to install the boot loader to the MBR or first sector of the hard disk. If you install it to the first sector, then you should be able to edit the boot.ini file for WinXP to point Fedora to HDB, therefore using NTloader to launch windows or grub (grub would then launch Fedora).
Its been a long time since I configured a dual boot system. Do a search on these forums as there's a couple HOWTO's on this.