I upgraded my PC to Windows 7 64 bit Home Premium - clean install. Since then I've tried to install the following SVN clients: Tortois 1.6.6 64bit and 32bit, Tortois 1.6.5 64bit, SlikSVN, SmartSVN, and a couple others. None of them will connect to ANY remote SVN repository.
Note: Everything works correctly when I plug in my old Vista HD with Tortoise 1.6.6 client installed. Therefore, I do not suspect the network per se.
I've seen some posts around with people running into similar issues on Windows 7 64bit but I've yet to see an actual answer/solution to the problem.