which OS, file format, what order?

i am going to put the operating system on my a150l 120gb , xsp will my main OS with programs installed. and other OS will be used so i can familarise mytself with them

i am thinking in this order for my 120gb
fat32 20gb xp pro
ext 10gb opensu or ubuntu
htf 10gb leapord but leapord uses 20gb am i right?
a data partition rest as fat32 /ntfs data for compatibility

i wont be using linux/leapord extensively to install apps , but mainly as OS just to play about with . so trying to minimuse disk space but my main OS will be XP ; so i have some questions
1 = i still want to be able to write 4gb + data files , so am i better off using xp partition as ntfs or fat32 or use the data partition as ntfs but then linux/leapord cannot access it without kernal add on so i am in chkicken egg situ here

2 opensu or ubuntu better? in terms of functionalily not just gui. i can program c++ , c , java so pretty competent using an OS if complex but neither do i want it DOS based

3 what order of OS do i install to get it tripe/dual boot

4 what program do i use to fdisk , create the partitions

5 what program do i use to create the boot menu options for the different OS ?

 

ok might leave xp as ntfs as found this http://www.fs-driver.org/download.html and leave data partition as fat32 so all OSs can access it