MrD -
Yes SI5.5 SP1 does have a 64-bit version available, you will just need the 64 bit installer. Shoot me an email at
dave.kirn@k2dealerservices.com and I will send you the 64 bit link.
As far as Visio 2007, I don't think that it is available in a 64 bit version - at least not that I am aware of.