I've searched around Microsoft's site, I've been able to find everything except a x64 version for windows 7.
I'm running Windows 7 x64 Professional
Is there any other version of "Windows Services for UNIX 3.x" I could use?
Services for UNIX 3.5 is an old version for previous versions of Windows.
Windows 7 comes with the current version of the Subsystem for UNIX-based applications. You can install it as a Windows component like you would install IIS. It is no longer a stand-alone product but a part of Windows.
Unfortunately it doesn't work on Windows 7 Professional, you need Enterprise or Ultimate.