hi , i need help i m thinking of putting linux on my system but i already have winxp, i f i put the linux on here i will need winxp disk to reformat harddrive want i

You should do a forum, and a google search for dual booting linux and windows. There are many sites/threads with this discussion, and you'll probably find your answer. The quick answer is no, you can boot windows from grub or lilo, armed with the afformentioned instructions. If windows is occuping your entire hard disk, you could use something like partition magic to free up some space. There are many considerations, so the question is quite tough to answer thoroughly. Hope this helps.
good luck.

youl need about 5 gig for freespace to put linux ona computer (this leaves LOADS of room for files and stuffs)

id advise you to defragment the windows disk beafore changing partisions

then you have 2 options:
you can change the size of your windows XP partision using winxp's fdisk utility, or a third party one like partision magic (which i think is the best) Failing that, most modern linux distros allow you to make formatting adjstments beafore you install the system

To change the size of winxp's partition using fdisk, don't you have t first wipe out your whole fixed disk, then partition it, then completely re-install win xp, on one partition, as well as install linux on the other partition? With partition magic you don't have to go thru wiping out your whole disk and then re-installing win xp. You just make a new partition out of the free space in the orig partition.

If you have two hard drives, you can put your linux distro on one drive and keep XP on the other. That would be easier and safer than dividing up a hard drive and doing a dual boot. If you make the linux drive the primary master, I believe that you could set up your Linux boot program (GRUB, LILO, or other) to boot either OS without even having to alter the MBR or anything else on the Windows XP drive.

If you must do a dual boot on a single hard drive, you will have to (dynamically) repartition the hard drive and you might have to reload the MBR data on the Windows partition after installing Linux. Make sure that your GRUB/LILO/whatever boot loader is configured for the dual boot. Don't rush in too quickly. Read the configuration instructions for the boot loader.

to resize your ntfs partition i would advise you to use bootit http://www.terabyteunlimited.com/bootitng.html
its a shareware and is a very convenient partition resizer...it fits on one single floppy .just remember not to install it to your hard drive but work from the bootable floppy that you have to make.