The firewire drive has to be shared in much the same way as the HD is shared. No share, No visible.
On the Firewire drive, exactly how is "formatted for both Windows and Mac" achieved?
The XP Firewall is probably not a problem as it only blocks incoming traffic and has no effect on outgoing stuff. If you can access the HD of the iBook then you should also be able to see the Firewire drive that is mounted on the desktop. How far down the iBook HD have you looked for stuff? Dig down in the Home folder/desktop and see what you can see. You should also be able to "see" the iBook through My Network Places and then Entire Network.
It does work, eventually
P
My roommate and I are trying to figure out this whole MAC to PC thing once and for all. The problem isn't that we can't see each other on the network, it's that I can't access his external HDD over the network.
My stuff:
HP Desktop (Windows ME)
IBM ThinkPad (Windows XP Home - SP2)
Linksys WRT54G (firmware 4.20.7) - Wireless (broadcasting Mixed B&G)and 4-port Ethernet
His stuff:
iBook G3 (OS X.3)
LACIE External HDD, connected to iBook thru FireWire 400 - formatted for both Windows and Mac.
PowerBook G4 (OS X.3) - not relevant, really.
The only computer physically plugged in to the router is my Desktop. The rest is all wireless. If more system info is required, I can post it in response.
I'm able to access the internal HD on the iBook from my ThinkPad, through his computer name and User ID (\\computername\username - only able to see folders on his HD, not his drives), but when I try to add his external drive to my Network Places in the same fashion (\\computername\drivename), XP says the ''folder name is not valid'' (because it can't see it, most likely). When I try to add just his computer name, it says I ''need a share to publish to.''
He is still investigating the user priveleges route, and I'd like to know if the router's firewall (or the XP firewall) could be blocking our progress. I also know there are issues with Virtual PC and FireWire, but I'm not sure if those issues are relevant to an actual PC (which doesn't have any firewire).
I've also read something about an ''Ad Hoc'' network on this forum, but I'm not sure what this is exactly.
Any help you could give us would be greatly appreciated.

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