No permission to use network resource, why?

I hope I am not abussing your kindness with this somewhat "O.T." topic...

I have a 1.7Gb file that I need to move from one pc to another at home. Both PCs connect with Ethernet cables (RJ-45) to the internet via a router (D-Link/DI-524) then a Cable modem (Arris-TM402P/110).
In the past I had no problem creating a home-network and have PCs share their files using Win2k. But this time for some reason it's got more complicated with WinXP Sad
PC 1 is running on WinXP Media Center Ed sp2, and No.2 is running on WinXP Pro version 2002.
I do see both PCs while in My Network Places/Microsoft Windows Network/MyWorkgroup/ . But when I try to access the remote PC it tells me:

"PC 2 is not accessible. You may not have permission to use this network resource. The network path was not found."

I have already shared the drive where the file is, I also turned on the Guest account, to no avail.
Btw, the 1st thing I tried was to prepare a Network Setup Disk in PC1 to run on PC2, but unfortunately instead of automatically setup/configure the PC2 it ended up opening the Network Wizard. I still continue playing along, but to no avail again I guess the disk is not working due to PC2 not using the same OS version, I mean, it doesn't even have sp2 installed, maybe this is the reason.

I don't get it, what am I missing?

Unfortunately PC2 doesn't have a CD burner much less a DVD burner, I don't have either a USB jumpdrive of 2Gb. And of course I don't have 2Gb worth of web space Sad This is why my most viable way would be my own home network.

Any ideas/suggestions will be greatly appreciated.
Thanks in advance guys Smile

JDL