By builders version, I can only guess the egg is referring to OEM copies? I've never seen a windows OS for sale online with builders version in the title or description.
Vista Home Basic and Home Premium have vastly differing features and functionality while Vista Business has slightly varied features over Home Premium when it comes down deep into the features list. For example, Vista Home Basic is exactly that - Vista and IE7. It doesn't include the Aero interface or anything to backup. Aside from the really basic standard OS stuff that is pretty much it. Home Premium includes media centre , Windows Movie Maker HD and premium games, while Vista Business differs slightly by removing the media functionality and adding fax, remote desktop (not included with Home Premium but hacks are around on the net) and complete pc backup functionality.
To put it simply, Vista Ultimate is a combination of both Home Premium and Business.
A run down of all the major features and comparisons between versions is available
here at microsoft.comVista Ultimate includes the BitLocker feature, however, I remember reading somewhere that parts of BitLocker are hardware dependant. More info
here.
At first glance, Home Premium is more feature rich over Business, for home usage at least. If you need more comprehensive backup facilities built into the OS, with remote desktop get Vista Business. However, if you want the media functionality plus the business functionality ... Vista Ultimate is probably the best purchase in the longterm.
You are right to guess the 64 bit version is good for using into the future. Vista x64 hasn't been sprung on the market like XP Pro x64 was. At one stage, microsoft compiled a list of applications that may have issues running on XP x64. New applications that have been Vista certified shouldn't have anywhere near as many problems.