I don't think you can access osx files from xp, but you can access files from xp in osx.
That said, there might be some 3rd party software to let you access osx from xp.
The best bet is to just set up a shared folder between the two systems.
If you format the windows partition as fat32, then you can read and write to it from osx. If you format it as NTFS, then you can only read.
I say you virtualize, and you'll have no problems.