Windows 7 & XP Shares: HELP!

[troymac1ure]

Okay, so I just spent 4 hours trying to get Windows 7 to recognize XP shares with no luck...almost.

I was helping a friend, there is a 2 computer network (both XP) with one sharing files. I was trying to get Windows 7 to recognize this share, but it doesn't even see the other computers (although they see it). So amongst all the stuff I tried, I checked Windows Update to find 8 patches and SP1 need to be installed. So I install the 8 patches first; it D/Ls the patches, then starts to create a restore point and *poof*, the two computers appear and are accessible.
(*NOTE* This is at the start of the restore point, it hadn't even begun installing the patches yet). So it finishes, I reboot and now they're gone again.
I install Win7 SP1, but to no avail. WTF?

Anyone? I have no idea left. I tried disabling firewalls, turning off XP's Simple Network and who knows what else. It's obviously something on the Windows 7 end, but this is my first dealings with 7, so I am looking for advice from those who are more familiar with it.