Ok...this is the way I would do it (actually this is almost like my laptop...XP, 98, FreeBSD). However, you will have no extended partition...is that ok?:
P1 - Primary with Dell (non-dos, but still eats up one of your 4 available primaries)
P2 - Primary with XP
P3 - Primary with 2K
P4 - Primary with 98
MAKE SURE YOU HAVE BOOT DISK FIRST!!!
Then, Set P2 to Active via Fdisk. Install XP. Boot with floppy. Set P3 active and install 2K. Boot with floppy. Set P4 active and install 98. Boot with floppy. Set P2 active. Reboot into XP. Find any boot manager you like (including Window's POS bootloader, but I recommend Powerquest's BootMagic) and plug away.
PS: If you decide to keep Window's POS bootloader, you will need to manually putz with the boot.ini file.
Typically it looks something like this...
[boot loader]
timeout=30
default=multi(0)disk(0)rdisk(0)partition(1)\WINDOWS
[operating systems]
multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Microsoft Windows XP Professional" /fastdetect
I would clone the "multi(0)...." line 3 times and (since I don't remember the specifics) start incrementing them....so it would look like....
[boot loader]
timeout=30
default=multi(0)disk(0)rdisk(0)partition(1)\WINDOWS
[operating systems]
multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Microsoft Windows XP Professional" /fastdetect
multi(0)disk(0)rdisk(0)partition(2)\WINDOWS="Microsoft Windows 2K Professional" /fastdetect
multi(0)disk(0)rdisk(0)partition(3)\WINDOWS="Microsoft Windows 98 Professional" /fastdetect
I believe that's the way it works....someone feel free to correct me. I'll go back to the office tomorrow and check.