Something that many people don't realise is that when Microsoft Windows is searching for files on a shared drive it can take longer than expected because Windows XP is checking for any Scheduled Tasks on the other P.C.
A simple Registry hack is all that's required to remedy this:
As with all tweaks that involve editing the registry, please do not attempt this unless you're confident and have sufficient backups, incorrectly editing the registry could render your system unusable.