why wont it boot?

[5pik3]

ok,i am building a computer for my son.not the latest and greatest by any means but he is 6 so im not gonna have anything too special.the motherboard is a P4SD-LA.the hard drive is a western digital 40 Gb ide.i got a really nice clean tricked out windows xp os.basic Ge force fx 5200 agp video card on the pci slot. 2.5 Gb of ram and thats it. very simple,or thats what i thought.oh and the cd drive it had was an ide toshiba,i believe.i replaced it with a sata sony opticarc cd/dvd rw disk drive. my plan was to just do a fresh install.i put everything together and powered it up,hit f1 to see that everything was good,and it was.i changed the boot order from the hdd to the optical drive.hit f10 and it booted and started the install of xp.on the setup screen it asked me where to put it.here is where i got kinda confused.there were 4 options. what i thought i could do was put just the os on the partition that was about 659.00Mb. my thinking was he could have about 33 or so Gb. of space for whatever. the other two partitions were not big at all.like 100mb. and 300 mb. everything went according to my plan.once i did the final restart,everything came up.i was able to put on the theme he wanted and name it and then it just stopped.no mouse movement or task manager..nothing.i waited without pressing any buttons and about a minute later it beeped and said i only had 120mb of memory on the hdd. ok fine,i swapped the hard drive with a seagate 500Gb sata hard drive.now i have both sata connections being used.hooked it up and fired it up and the new hdd was blank and i did the quick ntsf file system option and windows was installing.here is the kicker.the very first restart that it does,it goes through the normal boot diagnostics and it beeps. i read down the list and the last line reads
primary disk drive apati is non compatible.hit f1 to resume.so i hit that and im in bios.i jus kinda stopped there because im confused and dont want to just guess what the problem is.thank you for any info you can donate.i appreciate your time.

 

[Phillip Corcoran]

Can't make much sense of your post. I don't know which of us is more confused.
Might be a good idea to try again, make it clearer.