You have not disclosed your hardware configuration. There are too many variables to post a guide. Early versions of Windows 7 64bit suffered from a number of issues due to buggy motherboard and network drivers. Most of the issues were addressed on various Windows 7 forums in conjunction with the various Windows 7 64bit updates. Most of the issues were resolved with just a bios and driver updates.
I would suggest that you Google by your motherboard make and confirm that your bios and system drivers are all current versions; then read the Windows 7 forums for any current Windows 7 64bit networking issues.
http://www.sevenforums.com/tutorials/
http://www.windowsnetworking.com/
