Boot drive problems

[R.L. Grigg]

I'm having trouble with the boot drive on a MacBook Pro, and want to  
know if it's hosed or theres something more I can do with it. It's  
got Boot Camp on it and used to boot fine into Windows XP or OSX  
10.4.10. Now it will only boot into XP, not OSX. When I try, the  
machine hangs on the light gray Apple screen with the little round  
tikmark thingy circling forever. So I get into single user mode and  
run fsck:

localhost:/ root# /sbin/fsck -fy
** /dev/rdisk0s2
** Root file system
** Checking HFS Plus volume.
** Checking Extents Overflow file.
** Checking Catalog file.
    Incorrect number of thread records
(4, 220)
** Checking multi-linked files.
** Checking Catalog hierarchy.
    Invalid volume directory count
    (It should be 109046 instead of 109045)
    Invalid volume file count
    (It should be 487750 instead of 487736)
** Checking Extended Attributes file.
** Checking volume bitmap.
** Checking volume information.
** Repairing volume.
** Rechecking volume.

This repeats three times, then it says:

** The volume Macintosh HD could not be repaired after 3 attempts.

***** FILE SYSTEM WAS MODIFIED *****
localhost:/ root # Jul  2 10:46:13 launchd: Bug: launchd.c:492:30:  
chown(ourdir, getuid(), getuid()) != -1
Jul  2 10:46:13 launchd: Bug: launchd.c:492:30: chown(ourdir, getuid 
(), getuid()) != -1

Okay so I boot off the OSX installation disk and run Disk Utility to  
reformat the drive. The utility spits out a gazillion "Invalid node  
structure" messages then a billion "Invalid directory item count"  
messages and then quit's with:

Invalid directory item count
Invalid volume directory count
Invalid volume file count
The volume Macintosh HD could not be repaired after 3 attempts.

Is this thing savable? Is all the data lost? If the drive is  
physically hosed why does it boot into XP and run (seemingly) okay?  
Can I acces the OSX stuff from XP?
Russ