just need to shrink the partition in the vista pre-installed .. upto 15 Gb is enough for vista.
then install windows xp.. into one primary partition.. upto 10 Gb for windows XP.
leave the rest of hardisk space as an allocated space for linux. .
here must be careful with the rest of the process.. partitioning had a rule..
primary partition must not exceed 3 partition.. 😛
so manage the partition with full attention…
if you are planning to have one partition on / something around 20Gb unless you are planning for live cd creation later..
.. and the rest as one for /home .. in order to be a bit safer in case of somehow need re-formatting later..
so that you can spare the /home while the rest on / gone.. unless you do something really stupid 😛
after you have done with windows xp.. should repair the boot using Vista DVD.
recover the startup partition.. and it will detect the windows xp boot automatically ..
then can start with centos 5.1 installation.. and grub will take care the rest of the boot sequence..
if you ever messed up with boot up. try correction hd(0,0) to something as hd(0,1)..
because hd(0,0) actually the recovery partition from dell.. dunno if it safe to remove or not..
but I leave it there . in case of needing them some time later..
in centos you can customize all the interface to be something eye candy such as vista.. 😛
so that people never known whether you’re using linux or vista at the first glance…