Hard Drives, I know a little about. I can dig you out a decent cloning tool.
The stop error is an undocumented bad sector on your hard drive. Probably caused by general wear on the platter surface, and heads causing a tiny amount of dust inside your hard drive stopping a read occaisinaly. Hard drives, unless OEM, come with a warranty for a reason. They have definate lifespans. Some give a 1,000,000 hour usage guarantee, however if you read the fine print, that is running at like 2800 rpm. Which as we know is not the deal.
Personaly, i would clone an image of your hard drive to a new hard drive, then use disk managment in XP to partition the rest of the space on your new drive. As you will definatley buy a bigger drive. a)if your hard drive is old it WILL fail eventualy, if it isn't already b)it could be the hard drive showing signs of old age already.
I deal with about 50-100 hard drives a week, from personal and buisiness users, that have been using the same hard drive for more than three to four years. Honestly its worth the investment to replace them after about two to three years of regular use.