I don't think it's a problem specific to any build. Networking has been going strong for me on all of them, x86. This includes when my downstairs machine was only XPSP3 (which it's now only 7068 x86.)
I have all the drives mapped to there, and they're hidden with a $.
When I type \\ipaddresshere or \\computernamehere in windows explorer, it asks me for the user/pass, I put it, and expectedly it shows a screen with no shares. If I didn't hide them, all the shares would show. There are no errors in any of this for me.
I forget what default is, but I have the homegroup services on manual for startup type and they are not running at any given time I check. I also map computer names to ip addresses in the hosts file. The "use sharing wizard (recommended)" check box that you could find in windows explorer | organize | folder and search options | view tab I uncheck. I also assign static ips, give permissions to everyone and then only allow access to one machine, since that's all that's ever needed on my 2 pc, 1 ps3 network.
On my D-Link DI-624 router 100mbps, I am seeing up to between 10-11 megabytes per second between the 2 7068 boxes here.