Ok, you really need ANOTHER partition on the 110gigs. Yes, you have one partition (woohoo!) on the 10 gigs and you formatted it, I suspect the XP installation automatically formatted it for you. But you also need another file system on the 110 gigs. To have a file system you need to "format" it. And before you can format it, you need another partition on it.
As for buying partition magic....well, in your case, the solution is not very complicated. You could do just fine with the fdisk program that comes (I think?) with win XP. It's not got a cool GUI on it but it does the trick. Like the dude above said, run fdisk, select the last option and post the result here. Partition magic is only really useful if you're truying to change your partition sizes etc (ie. if you want ur 10 gig partition to really be 12 gigs, etc). For ur prob, partition magic is a waste of money.
Let us know how things go...