I believe that XP needs SP1 to see the entire hard drive, it has a 130 gig limit, you need to get SP1 installed before XP will allow you to use all of your drive.
The easiest solution is to have a Bootable windows xp cd with SP1 or SP2 already in it. Then you can boot and you will be able to see the 200 gig as one parition. Using an 'old' (non sp1) bootable win xp will only recognize the 128 gig limit due to limitation within that windows version.

Now I could be incorrect with this but this was the info I found on several sites. You might check also with the drive manufacturers website.