Check this link out: http://support.microsoft.com/kb/894435 I switched my internal sites over to x64 a few months back without any major problems. The only thing I remember that seemed a little tricky to me was the web service extensions. The 32bit dot net and 64bit dot net were actually listed seperatly, so after switching it over remember to enable the 64 bit or it will fail.
Knowledge is not power, however, the acquisition and appropriate application of knowledge can make you a very powerful individual.