Dual boot b/w XP Pro & 98SE?

The "best" way to set up a multi-boot system is to have separate drive partitions for each OS.

Then, start by installing the oldest OS first.

In your configuration,

Create a C: drive formatted in FAT16
Install W95

Create a D: drive formatted FAT16 or FAT32
Install W98

Create a E: drive, install XP.

If you boot into W98 and start the installation of XP it will detect the other operating systems and ask if you want to set up a dual / multi-boot system.

Alternately, you can use a boot controller such as Boot Commander

Or, install a hot swap bay for your boot drive, and swap drives to boot into different OSs.

Another option is the Trios drive selector.
You install multiple drives in the PC, and use the Trios switch to choose which drive to boot from.

Keep a close watch on your hardware. Make sure it is compatible with all versions of Windows desired.
Also, for Windows 95 or 98, you want to keep RAM below 511MB.
If you want / need more RAM for XP, you will need to add a maxmem statement to the boot files for the Windows 9X versions.

Chas