Are you sure you're on XP pro? If you're on XP pro you should just be able to import the disk. XP home edition cannot import foreign disks, you will have to convert it to basic. Foreign disk status happens when you import a dynamic disk from another Windows OS.
If you've confirmed you're on Pro and you can't select "import foreign disk" then there's probably some corruption in the OS.
Probably the easiest thing is to back up your data and convert to basic disk. You only need Dynamic disks if you're going to run some type of software RAID.