Well, I'M still running XP on all my machines... Half for older games and half because I'm a cheap SOB who won't cough up the $$$ to upgrade. :lol:
I haven't worked with Samba shares in a long long time, but I recall using a 3rd party protocol on my Windows machines instead of the default. I have no clue if there is something like that for Vista/XP, but it might be worthwhile looking into...