How do i get my xp computer to see my 300 gb hd?

you could be having a hardware problem rather than just windows not seeing your drive, it depends on your motherboard's ability to support that capacity drive!

what you need to do is provide the specs of your computer so readers can get an idea of what we're dealing with here so we will be better able to advice you, but in my opinion it more seems hardware than software problem, sometimes it could even be simply a jumper setting on your hard drive or mainboard that will allow windows to see your full capacity, it can be a sticky situation, check your board's BIOS also and see if updates are available for it as that could also be a problem too, in all of this i do wish you good luck.

You have to allocate the drive space when you set up windows. Put your xp cd back in and run the diagnostics and allocate the rest of your drive space and see if that doesn't solve your problem. Unless you made one huge partition initally, with all the space, that could be it.

You've got to re-install windows and delete the existing partition. You will need to backup your data.

You need to have the file system as NTFS FAT32 cant see big HDD